gen1recomp/docs/gold-walkthrough/asm-walk/section-25-lugia-gold-and-ho-oh-silver.md

Section 25 - Lugia (Gold) and Ho-Oh (Silver)

Source: ../section-25-lugia-gold-and-ho-oh-silver.txt Maps covered: ROUTE_41, WHIRL_ISLAND_NE, WHIRL_ISLAND_NW, WHIRL_ISLAND_SW, WHIRL_ISLAND_SE, WHIRL_ISLAND_CAVE, WHIRL_ISLAND_B1F, WHIRL_ISLAND_B2F, WHIRL_ISLAND_LUGIA_CHAMBER, ECRUTEAK_CITY, ECRUTEAK_TIN_TOWER_ENTRANCE, ECRUTEAK_TIN_TOWER_BACK_ENTRANCE, TIN_TOWER_1F .. TIN_TOWER_9F, TIN_TOWER_ROOF Badges / key milestones in this section: no badges. The milestone is catching the other version mascot post-Elite-Four - EVENT_FOUGHT_LUGIA / EVENT_FOUGHT_HO_OH, armed by the wing the Pewter City gramps hands over (maps/PewterCity.asm, PewterCityGrampsScript).

This section is two mutually exclusive branches. The walkthrough labels them "Whirl Islands - Gold Version" and "Tin Tower - Silver Version", and the asm agrees: Script_checkver (engine/overworld/scripting.asm:1471) returns GS_VERSION (constants/misc_constants.asm:21-23: 0 = Gold, 1 = Silver), so on each mascot the checkver / iftrue .Silver pair picks the level. In Gold, Lugia is level 70 and Ho-Oh was already caught at level 40; in Silver it is the mirror image.

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1. Route order

The walkthrough opens on the Magnet Train back to Johto - that hop belongs to the neighbouring Kanto section, and the only thing this section needs from it is that the player already holds the version-opposite wing.

Gold branch (Lugia, Whirl Islands)

#	Map constant	asm file	Enter via	Leaves via	Why (walkthrough beat)
1	OLIVINE_CITY	(fly target)	Fly	west connection to ROUTE_40 (data/maps/attributes.asm:145)	"Fly to Olivine City"
2	ROUTE_40	data/maps/attributes.asm:223	east connection from Olivine	south connection to ROUTE_41 (attributes.asm:224)	surf southwest
3	ROUTE_41	maps/Route41.asm	north connection from Route 40	warp_event 36, 19 (warp 2)	"surf southwest and west until you reach the northeast cave", clearing whirlpools
4	WHIRL_ISLAND_NE	maps/WhirlIslandNE.asm	warp 1 (3, 13)	warp 2 (17, 3) or warp 3 (13, 11)	Flash, ledges, ULTRA_BALL at (11, 11)
5	WHIRL_ISLAND_B1F	maps/WhirlIslandB1F.asm	warp 2 (35, 3) / warp 3 (29, 9)	warp 7 (25, 21) or warp 8 (13, 27)	ledge chain, ESCAPE_ROPE at (19, 26), CALCIUM at (33, 23)
6	WHIRL_ISLAND_CAVE	maps/WhirlIslandCave.asm	B1F warp 9 (17, 21) -> Cave warp 1 (7, 5)	Cave warp 2 (3, 13) -> WHIRL_ISLAND_NW	"head out the door to breathe, but that's pointless"
7	WHIRL_ISLAND_SW	maps/WhirlIslandSW.asm	B1F warp 4 (9, 31) / warp 5 (23, 31)	warp 5 (17, 15) -> B2F warp 4	GUARD_SPEC at (15, 2)
8	WHIRL_ISLAND_B2F	maps/WhirlIslandB2F.asm	warp 1 (11, 5) from B1F warp 7	warp 3 (7, 25)	MAX_REVIVE (6, 4), waterfall descent, "head left and through the door"
9	WHIRL_ISLAND_LUGIA_CHAMBER	maps/WhirlIslandLugiaChamber.asm	warp 1 (9, 13)	Escape Rope (environment is CAVE)	surf north to Lugia at (9, 5)

Silver branch (Ho-Oh, Tin Tower)

#	Map constant	asm file	Enter via	Leaves via	Why (walkthrough beat)
1	ECRUTEAK_CITY	maps/EcruteakCity.asm	Fly	warp 3 (18, 11)	"Go back to Ecruteak City"
2	ECRUTEAK_TIN_TOWER_ENTRANCE	maps/EcruteakTinTowerEntrance.asm	warp 1 (4, 17) / warp 2 (5, 17)	warp 3 (5, 3) -> warp 4 (17, 15), then warp 5 (17, 3)	"the Bell Tower entry house. Talk to the man"
3	ECRUTEAK_TIN_TOWER_BACK_ENTRANCE	maps/EcruteakTinTowerBackEntrance.asm	warp 3 (2, 4)	warp 1 (7, 4) / warp 2 (7, 5) -> ECRUTEAK_CITY warps 4/5 (20, 2) (20, 3)	"follow up the trail to the tower itself"
4	ECRUTEAK_CITY (north strip)	maps/EcruteakCity.asm	warps 4/5	warp 12 (37, 7)	walk east along the fenced strip to Tin Tower
5	TIN_TOWER_1F	maps/TinTower1F.asm	warp 1 (9, 15) / warp 2 (10, 15)	warp 3 (10, 2)	"another bald man will let you through" - the sage occupies the stair tile
6	TIN_TOWER_2F	maps/TinTower2F.asm	warp 2 (10, 2)	warp 1 (10, 14)	"wild Rattatas will start converging on you"
7	TIN_TOWER_3F	maps/TinTower3F.asm	warp 1 (10, 14)	warp 2 (16, 2)	FULL_HEAL at (3, 14), jump-ledge puzzle
8	TIN_TOWER_4F	maps/TinTower4F.asm	warp 2 (16, 2)	warps 1 (2, 4), 3 (2, 14), 4 (17, 15)	ULTRA_BALL, SUPER_POTION, ESCAPE_ROPE
9	TIN_TOWER_5F	maps/TinTower5F.asm	warps 2/3/4	warp 1 (11, 15)	RARE_CANDY at (9, 9)
10	TIN_TOWER_6F	maps/TinTower6F.asm	warp 2 (11, 15)	warp 1 (3, 9)	"go up and you'll get a Max Potion" (see Unresolved)
11	TIN_TOWER_7F	maps/TinTower7F.asm	warp 1 (3, 9)	warp 2 (10, 15), plus in-floor warp pair 3/4 and warp 5 to 9F	MAX_REVIVE at (16, 1); "go through the next two warps"
12	TIN_TOWER_8F	maps/TinTower8F.asm	warp 1 (2, 5)	warps 2-6 into 9F	NUGGET, MAX_ELIXER, FULL_RESTORE
13	TIN_TOWER_9F	maps/TinTower9F.asm	warps 1/2/3/5/6/7 from 7F+8F	warp 4 (7, 9)	"cross the planks down, then go up the ladder"
14	TIN_TOWER_ROOF	maps/TinTowerRoof.asm	warp 1 (9, 13)	back down warp 1 then Escape Rope	level-70 Ho-Oh at (9, 5)

The walkthrough's closing line ("ride the Magnet Train back to Kanto and fly back to Pewter City") hands off to the next section; nothing on that hop is resolved here.

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2. Maps

ROUTE_41

• Script: maps/Route41.asm
• Blocks: maps/Route41.blk
• Header: data/maps/maps.asm:443 -> TILESET_JOHTO, ROUTE, LANDMARK_ROUTE_41, MUSIC_ROUTE_36, phone FALSE, PALETTE_AUTO, FISHGROUP_OCEAN
• Dimensions: constants/map_constants.asm:410 -> map_const ROUTE_41, 25, 27 (group 22 CIANWOOD, map 2)
• Connections (data/maps/attributes.asm:227-229): north Route40, west CianwoodCity

Warps (def_warp_events)

idx	x	y	destination map	dest warp
1	12	17	WHIRL_ISLAND_NW	1
2	36	19	WHIRL_ISLAND_NE	1
3	12	37	WHIRL_ISLAND_SW	1
4	36	45	WHIRL_ISLAND_SE	1

Coord events: none.

BG events (def_bg_events)

x	y	type	script/item
9	35	BGEVENT_ITEM	Route41HiddenMaxEther -> hiddenitem MAX_ETHER, EVENT_ROUTE_41_HIDDEN_MAX_ETHER

Object events (def_object_events)

const	sprite	x	y	movement	type	script label	event flag
ROUTE41_OLIVINE_RIVAL1	SPRITE_OLIVINE_RIVAL	32	6	SPINRANDOM_FAST	OBJECTTYPE_TRAINER (sight 3)	TrainerSwimmermCharlie	-1
ROUTE41_OLIVINE_RIVAL2	SPRITE_OLIVINE_RIVAL	46	8	SPINRANDOM_FAST	OBJECTTYPE_TRAINER (3)	TrainerSwimmermGeorge	-1
ROUTE41_OLIVINE_RIVAL3	SPRITE_OLIVINE_RIVAL	20	26	SPINCOUNTERCLOCKWISE	OBJECTTYPE_TRAINER (3)	TrainerSwimmermBerke	-1
ROUTE41_OLIVINE_RIVAL4	SPRITE_OLIVINE_RIVAL	32	30	SPINCLOCKWISE	OBJECTTYPE_TRAINER (3)	TrainerSwimmermKirk	-1
ROUTE41_OLIVINE_RIVAL5	SPRITE_OLIVINE_RIVAL	19	46	SPINCOUNTERCLOCKWISE	OBJECTTYPE_TRAINER (3)	TrainerSwimmermMathew	-1
ROUTE41_SWIMMER_GIRL1	SPRITE_SWIMMER_GIRL	17	4	SPINRANDOM_FAST	OBJECTTYPE_TRAINER (3)	TrainerSwimmerfKaylee	-1
ROUTE41_SWIMMER_GIRL2	SPRITE_SWIMMER_GIRL	23	19	STANDING_UP	OBJECTTYPE_TRAINER (3)	TrainerSwimmerfSusie	-1
ROUTE41_SWIMMER_GIRL3	SPRITE_SWIMMER_GIRL	27	34	STANDING_LEFT	OBJECTTYPE_TRAINER (3)	TrainerSwimmerfDenise	-1
ROUTE41_SWIMMER_GIRL4	SPRITE_SWIMMER_GIRL	44	28	STANDING_RIGHT	OBJECTTYPE_TRAINER (4)	TrainerSwimmerfKara	-1
ROUTE41_SWIMMER_GIRL5	SPRITE_SWIMMER_GIRL	9	50	SPINRANDOM_FAST	OBJECTTYPE_TRAINER (2)	TrainerSwimmerfWendy	-1

Note the sight ranges: Kara is 4, the widest on the route, which is why the walkthrough uses her as the landmark for the northeast whirlpool ("the whirlpool is just northwest of where you fought Swimmer Kara"). Her object sits at (44, 28); the trainer flag is EVENT_BEAT_SWIMMERF_KARA, so once beaten she is still standing there (event flag on the row is -1, i.e. never masked) and still walks into your path - the walkthrough's joke about swimmer stamina is literally the object table.

Scripts of interest

• TrainerSwimmerfKara - trainer SWIMMERF, KARA, EVENT_BEAT_SWIMMERF_KARA, .... Post-battle it only prints SwimmerfKaraAfterBattleText ("I heard roars from deep inside the ISLANDS"). No flag beyond the beat flag, no gate.

Whirlpools: they are map blocks, not events. data/collision/field_move_blocks.asm:48-55 gives WhirlpoolBlockPointers -> TILESET_JOHTO -> db $07, $36, 0 (facing block $07, replacement $36, animation type 0). A bot that wants the whirlpool coordinates has to scan maps/Route41.blk for block id $07; the collision value under it is COLL_WHIRLPOOL $24 (constants/collision_constants.asm:27, tested by CheckWhirlpoolTile, home/map_objects.asm:176-183).

Wild encounters

• Surfing, data/wild/johto_water.asm:170-181, def_water_wildmons ROUTE_41, encounter rate 6 percent. Gold: 20 TENTACOOL, 20 TENTACRUEL, 20 MANTINE. Silver: 20 TENTACOOL, 20 TENTACRUEL, 15 TENTACOOL.
• Fishing: header fish group is FISHGROUP_OCEAN (data/wild/fish.asm:13, .Ocean_Old/.Ocean_Good/.Ocean_Super).
• The walkthrough's Max Repel advice is aimed squarely at this 6% table.

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WHIRL_ISLAND_NE

• Script: maps/WhirlIslandNE.asm
• Blocks: maps/WhirlIslandNE.blk
• Header: data/maps/maps.asm:137 -> TILESET_DARK_CAVE, CAVE, LANDMARK_WHIRL_ISLANDS, MUSIC_UNION_CAVE, phone TRUE, PALETTE_DARK, FISHGROUP_WHIRL_ISLANDS
• Dimensions: constants/map_constants.asm:124 -> map_const WHIRL_ISLAND_NE, 10, 9 (group 3 DUNGEONS, map 59)
• Connections: none (island interior).

Warps

idx	x	y	destination map	dest warp
1	3	13	ROUTE_41	2
2	17	3	WHIRL_ISLAND_B1F	2
3	13	11	WHIRL_ISLAND_B1F	3

Coord events: none. BG events: none.

Object events

const	sprite	x	y	movement	type	script label	event flag
WHIRLISLANDNE_POKE_BALL	SPRITE_POKE_BALL	11	11	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandNEUltraBall (47:401e)	EVENT_WHIRL_ISLAND_NE_ULTRA_BALL

WhirlIslandNEUltraBall is a bare itemball ULTRA_BALL.

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WHIRL_ISLAND_NW

• Script: maps/WhirlIslandNW.asm - no scripts at all, warps only
• Blocks: maps/WhirlIslandNW.blk
• Header: data/maps/maps.asm:136, same row shape as NE
• Dimensions: constants/map_constants.asm:123 -> 5, 9 (group 3, map 58)

Warps

idx	x	y	destination map	dest warp
1	5	7	ROUTE_41	1
2	5	3	WHIRL_ISLAND_B1F	1
3	3	15	WHIRL_ISLAND_SW	4
4	7	15	WHIRL_ISLAND_CAVE	2

No coord events, bg events or objects.

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WHIRL_ISLAND_SW

• Script: maps/WhirlIslandSW.asm
• Blocks: maps/WhirlIslandSW.blk
• Header: data/maps/maps.asm:138
• Dimensions: constants/map_constants.asm:125 -> 10, 9 (group 3, map 60)

Warps

idx	x	y	destination map	dest warp
1	5	7	ROUTE_41	3
2	17	3	WHIRL_ISLAND_B1F	5
3	3	3	WHIRL_ISLAND_B1F	4
4	3	15	WHIRL_ISLAND_NW	3
5	17	15	WHIRL_ISLAND_B2F	4

Coord events: none. BG events: none.

Object events

const	sprite	x	y	movement	type	script label	event flag
WHIRLISLANDSW_POKE_BALL	SPRITE_POKE_BALL	15	2	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandSWGuardSpec (47:4044)	EVENT_WHIRL_ISLAND_SW_GUARD_SPEC

itemball GUARD_SPEC - the walkthrough's "Guard Specs".

Wild encounters: surfing, data/wild/johto_water.asm:79-84, def_water_wildmons WHIRL_ISLAND_SW, rate 4 percent: 20 TENTACOOL, 15 HORSEA, 20 TENTACRUEL.

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WHIRL_ISLAND_SE

• Script: maps/WhirlIslandSE.asm - warps only
• Blocks: maps/WhirlIslandSE.blk
• Header: data/maps/maps.asm:140
• Dimensions: constants/map_constants.asm:127 -> 5, 9 (group 3, map 62)

Warps

idx	x	y	destination map	dest warp
1	5	13	ROUTE_41	4
2	5	3	WHIRL_ISLAND_B1F	6

No coord events, bg events or objects. No water encounter table.

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WHIRL_ISLAND_CAVE

• Script: maps/WhirlIslandCave.asm - warps only
• Blocks: maps/WhirlIslandCave.blk
• Header: data/maps/maps.asm:139
• Dimensions: constants/map_constants.asm:126 -> 5, 9 (group 3, map 61)

Warps

idx	x	y	destination map	dest warp
1	7	5	WHIRL_ISLAND_B1F	9
2	3	13	WHIRL_ISLAND_NW	4

This is the "you can now head out the door to breathe, but that's pointless" room: it is a pure corridor between B1F and the NW island.

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WHIRL_ISLAND_B1F

• Script: maps/WhirlIslandB1F.asm (47:4096 WhirlIslandB1F_MapScripts)
• Blocks: maps/WhirlIslandB1F.blk (2b:6f61 WhirlIslandB1F_Blocks)
• Header: data/maps/maps.asm:141
• Dimensions: constants/map_constants.asm:128 -> 20, 18 (group 3, map 63)

Warps

idx	x	y	destination map	dest warp
1	5	5	WHIRL_ISLAND_NW	2
2	35	3	WHIRL_ISLAND_NE	2
3	29	9	WHIRL_ISLAND_NE	3
4	9	31	WHIRL_ISLAND_SW	3
5	23	31	WHIRL_ISLAND_SW	2
6	31	29	WHIRL_ISLAND_SE	2
7	25	21	WHIRL_ISLAND_B2F	1
8	13	27	WHIRL_ISLAND_B2F	2
9	17	21	WHIRL_ISLAND_CAVE	1

Coord events: none.

BG events

x	y	type	script/item
30	4	BGEVENT_ITEM	WhirlIslandB1FHiddenRareCandy -> hiddenitem RARE_CANDY, EVENT_WHIRL_ISLAND_B1F_HIDDEN_RARE_CANDY
36	18	BGEVENT_ITEM	WhirlIslandB1FHiddenUltraBall -> hiddenitem ULTRA_BALL, EVENT_WHIRL_ISLAND_B1F_HIDDEN_ULTRA_BALL
2	23	BGEVENT_ITEM	WhirlIslandB1FHiddenFullRestore -> hiddenitem FULL_RESTORE, EVENT_WHIRL_ISLAND_B1F_HIDDEN_FULL_RESTORE

Object events

const	sprite	x	y	movement	type	script label	event flag
WHIRLISLANDB1F_POKE_BALL1	SPRITE_POKE_BALL	7	13	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandB1FFullRestore	EVENT_WHIRL_ISLAND_B1F_FULL_RESTORE
WHIRLISLANDB1F_POKE_BALL2	SPRITE_POKE_BALL	2	18	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandB1FCarbos	EVENT_WHIRL_ISLAND_B1F_CARBOS
WHIRLISLANDB1F_POKE_BALL3	SPRITE_POKE_BALL	33	23	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandB1FCalcium	EVENT_WHIRL_ISLAND_B1F_CALCIUM
WHIRLISLANDB1F_POKE_BALL4	SPRITE_POKE_BALL	17	8	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandB1FNugget	EVENT_WHIRL_ISLAND_B1F_NUGGET
WHIRLISLANDB1F_POKE_BALL5	SPRITE_POKE_BALL	19	26	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandB1FEscapeRope	EVENT_WHIRL_ISLAND_B1F_ESCAPE_ROPE
WHIRLISLANDB1F_BOULDER	SPRITE_BOULDER	23	26	SPRITEMOVEDATA_STRENGTH_BOULDER	OBJECTTYPE_SCRIPT	WhirlIslandB1FBoulder (jumpstd StrengthBoulderScript)	-1

The boulder at (23, 26) sits two tiles east of the Escape Rope ball and is the only Strength object in the dungeon. The walkthrough never mentions it.

Wild encounters: grass/cave-floor, data/wild/johto_grass.asm:1213-1239, def_grass_wildmons WHIRL_ISLAND_B1F, rates 6 percent for all three times of day, and the morn/day/nite slot lists are identical: 23 KRABBY, 24 ZUBAT, 25 KRABBY, 23 SEEL, 24 GOLBAT, 25 SEEL, 25 SEEL. No water table for B1F.

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WHIRL_ISLAND_B2F

• Script: maps/WhirlIslandB2F.asm
• Blocks: maps/WhirlIslandB2F.blk
• Header: data/maps/maps.asm:142
• Dimensions: constants/map_constants.asm:129 -> 10, 18 (group 3, map 64)

Warps

idx	x	y	destination map	dest warp
1	11	5	WHIRL_ISLAND_B1F	7
2	7	11	WHIRL_ISLAND_B1F	8
3	7	25	WHIRL_ISLAND_LUGIA_CHAMBER	1
4	13	31	WHIRL_ISLAND_SW	5

Coord events: none. BG events: none.

Object events

const	sprite	x	y	movement	type	script label	event flag
WHIRLISLANDB2F_POKE_BALL1	SPRITE_POKE_BALL	10	11	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandB2FFullRestore	EVENT_WHIRL_ISLAND_B2F_FULL_RESTORE
WHIRLISLANDB2F_POKE_BALL2	SPRITE_POKE_BALL	6	4	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandB2FMaxRevive	EVENT_WHIRL_ISLAND_B2F_MAX_REVIVE
WHIRLISLANDB2F_POKE_BALL3	SPRITE_POKE_BALL	5	12	STILL	OBJECTTYPE_ITEMBALL	WhirlIslandB2FMaxElixer	EVENT_WHIRL_ISLAND_B2F_MAX_ELIXER

(6, 4) is the single MAX_REVIVE in the whole Whirl Islands (see Unresolved for the walkthrough's "Max Revive x2").

Wild encounters

• Floor: data/wild/johto_grass.asm:1241-1267, rate 6 percent, identical to B1F (23 KRABBY / 24 ZUBAT / 25 KRABBY / 23 SEEL / 24 GOLBAT / 25 SEEL / 25 SEEL).
• Water: data/wild/johto_water.asm:86-91, rate 4 percent: 15 HORSEA, 20 HORSEA, 20 TENTACRUEL.

The "two items on the cliff but you can't reach those" line matches the two balls on the west shelf ((5, 12) Max Elixer and (10, 11) Full Restore are reachable from the other side of the floor; exactly which two the FAQ means is a .blk question, see Unresolved).

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WHIRL_ISLAND_LUGIA_CHAMBER

• Script: maps/WhirlIslandLugiaChamber.asm (47:418c callback, 47:41a0 Lugia)
• Blocks: maps/WhirlIslandLugiaChamber.blk (2b:717d)
• Header: data/maps/maps.asm:143 -> TILESET_DARK_CAVE, CAVE, LANDMARK_WHIRL_ISLANDS, MUSIC_UNION_CAVE, phone TRUE, PALETTE_DARK, FISHGROUP_WHIRL_ISLANDS
• Dimensions: constants/map_constants.asm:130 -> 10, 9 (group 3, map 65)

Warps

idx	x	y	destination map	dest warp
1	9	13	WHIRL_ISLAND_B2F	3

Coord events: none. BG events: none.

Object events

const	sprite	x	y	movement	type	script label	event flag
WHIRLISLANDLUGIACHAMBER_LUGIA	SPRITE_LUGIA	9	5	SPRITEMOVEDATA_POKEMON	OBJECTTYPE_SCRIPT, palette PAL_NPC_BLUE	Lugia	EVENT_WHIRL_ISLAND_LUGIA_CHAMBER_LUGIA

Scripts of interest

• WhirlIslandLugiaChamberLugiaCallback - callback MAPCALLBACK_OBJECTS. checkevent EVENT_FOUGHT_LUGIA / iftrue .NoAppear, then checkitem SILVER_WING / iftrue .Appear, else .NoAppear. So Lugia is on the map only while the SILVER_WING is in the bag and the fight has not happened. The wing is a checkitem, not an event - selling or storing it makes Lugia vanish again.
• Lugia (47:41a0) - faceplayer, opentext, writetext LugiaText ("Gyaaas!"), cry LUGIA, pause 15, closetext, setevent EVENT_FOUGHT_LUGIA, checkver, iftrue .Silver.
  • Gold arm: loadvar VAR_BATTLETYPE, BATTLETYPE_FORCEITEM, loadwildmon LUGIA, 70, startbattle, disappear WHIRLISLANDLUGIACHAMBER_LUGIA, reloadmapafterbattle, end.
  • .Silver: identical but loadwildmon LUGIA, 40.
  • EVENT_FOUGHT_LUGIA is set before the battle, so fleeing, fainting or knocking it out all consume the encounter. This is exactly why the walkthrough insists on saving first: there is no re-arm path in the asm.
  • BATTLETYPE_FORCEITEM (constants/battle_constants.asm:101) makes InitEnemyMon's .WildItem arm hand over wBaseItem1 unconditionally (engine/battle/core.asm:5765-5773). Lugia's data/pokemon/base_stats/lugia.asm row is db NO_ITEM, NO_ITEM, so it holds nothing - the forced-item type is inherited boilerplate here.

Flags and events

constant	defined in	read/written by	meaning for a bot
EVENT_FOUGHT_LUGIA	constants/event_flags.asm:455	read by the callback, set by Lugia before startbattle	one-shot. Once set, Lugia never reappears
EVENT_WHIRL_ISLAND_LUGIA_CHAMBER_LUGIA	constants/event_flags.asm:1247	the object row's mask flag, driven by appear/disappear	object visibility only
EVENT_GOT_SILVER_WING	constants/event_flags.asm:130	set by PewterCityGrampsScript (Gold) / RadioTower5F (Silver)	prerequisite for holding SILVER_WING

Wild encounters

• Floor: data/wild/johto_grass.asm:1269-1295, rate 6 percent: 24 KRABBY, 25 ZUBAT, 26 KRABBY, 24 SEEL, 25 GOLBAT, 26 SEEL, 26 SEEL.
• Water: data/wild/johto_water.asm:93-98, rate 4 percent: 20 HORSEA, 20 TENTACRUEL, 20 SEADRA. This is the only Seadra slot in the dungeon, and it is on the water directly in front of Lugia.

Catch math (data/pokemon/base_stats/lugia.asm): db 3 ; catch rate. UltraBallMultiplier doubles it to 6; HeavyBallMultiplier (engine/items/item_effects.asm:752) adds a flat offset by dex weight, and Lugia's dex weight is 4760 tenths of a pound = 216 kg (data/pokemon/dex_entries/gold/lugia.asm), which lands in the +20 bracket -> effective 23. Thard_Verad's tip in the FAQ is correct and is worth ~4x the Ultra Ball rate.

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ECRUTEAK_CITY (transit only)

• Script: maps/EcruteakCity.asm
• Header: data/maps/maps.asm:173 -> TILESET_JOHTO, TOWN, LANDMARK_ECRUTEAK_CITY, MUSIC_ECRUTEAK_CITY, phone FALSE, PALETTE_AUTO, FISHGROUP_POND
• Dimensions: constants/map_constants.asm:159 -> 20, 18 (group 4, map 9)

Warps (only the rows this section uses)

idx	x	y	destination map	dest warp
3	18	11	ECRUTEAK_TIN_TOWER_ENTRANCE	1
4	20	2	ECRUTEAK_TIN_TOWER_BACK_ENTRANCE	1
5	20	3	ECRUTEAK_TIN_TOWER_BACK_ENTRANCE	2
12	37	7	TIN_TOWER_1F	1
13	5	5	BURNED_TOWER_1F	1

There is a bg_event 38, 10, BGEVENT_READ, TinTowerSign next to the tower door.

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ECRUTEAK_TIN_TOWER_ENTRANCE

• Script: maps/EcruteakTinTowerEntrance.asm
• Blocks: maps/EcruteakTinTowerEntrance.blk
• Header: data/maps/maps.asm:165 -> TILESET_TOWER, INDOOR, LANDMARK_ECRUTEAK_CITY, MUSIC_ECRUTEAK_CITY, phone FALSE, PALETTE_DAY, FISHGROUP_SHORE
• Dimensions: constants/map_constants.asm:151 -> 10, 9 (group 4, map 1)

Warps

idx	x	y	destination map	dest warp
1	4	17	ECRUTEAK_CITY	3
2	5	17	ECRUTEAK_CITY	3
3	5	3	ECRUTEAK_TIN_TOWER_ENTRANCE	4
4	17	15	ECRUTEAK_TIN_TOWER_ENTRANCE	3
5	17	3	ECRUTEAK_TIN_TOWER_BACK_ENTRANCE	3

Warps 3 and 4 are a self-referential pair: the map holds two disconnected corridors and the "walk up the stairs" is a same-map teleport from (5, 3) to (17, 15).

Coord events

scene	x	y	script label	effect
SCENE_ECRUTEAKTINTOWERENTRANCE_SAGE_BLOCKS (0)	4	7	EcruteakTinTowerEntranceSageBlocksLeft (52:400c)	sage 2 side-steps LEFT, sage 1 is moveobjectd to (4, 6) and appeared, sage 2 disappears
SCENE_ECRUTEAKTINTOWERENTRANCE_SAGE_BLOCKS (0)	5	7	EcruteakTinTowerEntranceSageBlocksRight (52:4021)	mirror image, sage 2 ends at (5, 6)

Scene ids come from the scene_script macro's inline const block (macros/scripts/maps.asm:12-33): SAGE_BLOCKS = 0, NOOP = 1. Both scene bodies are end; the scene id exists only to arm/disarm the two coord events.

BG events: none.

Object events

const	sprite	x	y	movement	type	script label	event flag
ECRUTEAKTINTOWERENTRANCE_SAGE1	SPRITE_SAGE	4	6	STANDING_DOWN	OBJECTTYPE_SCRIPT	EcruteakTinTowerEntranceSageScript (52:4037)	EVENT_ECRUTEAK_TIN_TOWER_ENTRANCE_SAGE_LEFT
ECRUTEAKTINTOWERENTRANCE_SAGE2	SPRITE_SAGE	5	6	STANDING_DOWN	OBJECTTYPE_SCRIPT	EcruteakTinTowerEntranceSageScript	EVENT_ECRUTEAK_TIN_TOWER_ENTRANCE_SAGE_RIGHT
ECRUTEAKTINTOWERENTRANCE_SAGE3	SPRITE_SAGE	6	9	WANDER (1,1)	OBJECTTYPE_SCRIPT	EcruteakTinTowerEntranceWanderingSageScript (52:404b)	-1
ECRUTEAKTINTOWERENTRANCE_GRAMPS	SPRITE_GRAMPS	3	11	WANDER (1,1)	OBJECTTYPE_SCRIPT	EcruteakTinTowerEntranceGrampsScript	-1

Object rows are masked when their flag is set (CheckObjectFlag, engine/overworld/map_objects_2.asm:32-61: EventFlagAction/CHECK_FLAG non-zero -> .masked). InitializeEventsScript (engine/events/std_scripts.asm:438, line 533) does setevent EVENT_ECRUTEAK_TIN_TOWER_ENTRANCE_SAGE_LEFT at new game, so on a fresh save only SAGE2 at (5, 6) is standing there.

Scripts of interest

• EcruteakTinTowerEntranceSageScript - faceplayer, opentext, checkflag ENGINE_FOGBADGE, iftrue .BlockPassage_GotFogBadge. Both arms are pure text (EcruteakTinTowerEntranceSageText vs ..._GotFogBadge); the script never opens the path.
• The actual unblock is maps/EcruteakGym.asm:34: setmapscene ECRUTEAK_TIN_TOWER_ENTRANCE, SCENE_ECRUTEAKTINTOWERENTRANCE_NOOP, run in the same block as setflag ENGINE_FOGBADGE after beating Morty. With the scene at NOOP the two coord events no longer match and the sage never steps into the doorway. By section 25 the player has all 16 badges, so this is already open - the walkthrough's "talk to the man and he'll let you through" is flavour text, not a required action.
• EcruteakTinTowerEntranceWanderingSageScript - checkevent EVENT_GOT_RAINBOW_WING; the post-wing line is "The TIN TOWER shook! A #MON must have returned to the top!". This is the only in-map confirmation that Ho-Oh is now spawnable.

---

ECRUTEAK_TIN_TOWER_BACK_ENTRANCE

• Script: maps/EcruteakTinTowerBackEntrance.asm - warps only, no scripts
• Blocks: maps/EcruteakTinTowerBackEntrance.blk
• Header: data/maps/maps.asm:166 -> TILESET_TRADITIONAL_HOUSE, INDOOR, LANDMARK_ECRUTEAK_CITY, MUSIC_ECRUTEAK_CITY, phone FALSE, PALETTE_DAY, FISHGROUP_SHORE
• Dimensions: constants/map_constants.asm:152 -> 4, 4 (group 4, map 2)

Warps

idx	x	y	destination map	dest warp
1	7	4	ECRUTEAK_CITY	4
2	7	5	ECRUTEAK_CITY	5
3	2	4	ECRUTEAK_TIN_TOWER_ENTRANCE	5

---

TIN_TOWER_1F

• Script: maps/TinTower1F.asm (42:4b1d TinTowerSageScript)
• Blocks: maps/TinTower1F.blk
• Header: data/maps/maps.asm:82 -> TILESET_TOWER, DUNGEON, LANDMARK_TIN_TOWER, MUSIC_TIN_TOWER, phone FALSE, PALETTE_DAY, FISHGROUP_SHORE
• Dimensions: constants/map_constants.asm:69 -> 10, 9 (group 3, map 4)

Warps

idx	x	y	destination map	dest warp
1	9	15	ECRUTEAK_CITY	12
2	10	15	ECRUTEAK_CITY	12
3	10	2	TIN_TOWER_2F	2

Coord events: none. BG events: none.

Object events

const	sprite	x	y	movement	type	script label	event flag
TINTOWER1F_SAGE	SPRITE_SAGE	10	2	STANDING_DOWN	OBJECTTYPE_SCRIPT	TinTowerSageScript	EVENT_TEAM_ROCKET_DISBANDED

This is the real gate for the whole Silver branch. The sage's coordinates are (10, 2), byte-for-byte the coordinates of warp 3. While the object is visible the stair tile is occupied and 2F is unreachable. The object is masked - i.e. the sage disappears - when EVENT_TEAM_ROCKET_DISBANDED (constants/event_flags.asm:1283) is set, and that flag is only ever set by the two Rainbow Wing hand-offs:

• maps/RadioTower5F.asm:124-130 (Gold): verbosegiveitem RAINBOW_WING (124), setevent EVENT_GOT_RAINBOW_WING (129), setevent EVENT_TEAM_ROCKET_DISBANDED (130).
• maps/PewterCity.asm:42-51 .RainbowWing (Silver): the gramps gives RAINBOW_WING (49), setevent EVENT_GOT_RAINBOW_WING (50), setevent EVENT_TEAM_ROCKET_DISBANDED (51).

So the walkthrough's "another bald man will let you through because you have the beautiful Rainbow Wing" is literally true, but the mechanism is a masked object keyed on EVENT_TEAM_ROCKET_DISBANDED, not a checkitem RAINBOW_WING.

Wild encounters: none - TIN_TOWER_1F has no def_grass_wildmons row (data/wild/johto_grass.asm starts the tower at TIN_TOWER_2F, line 61).

---

TIN_TOWER_2F

• Script: maps/TinTower2F.asm - warps only
• Blocks: maps/TinTower2F.blk
• Header: data/maps/maps.asm:83; Dimensions constants/map_constants.asm:70 -> 10, 9 (group 3, map 5)

Warps

idx	x	y	destination map	dest warp
1	10	14	TIN_TOWER_3F	1
2	10	2	TIN_TOWER_1F	3

Wild encounters: data/wild/johto_grass.asm:61-87, def_grass_wildmons TIN_TOWER_2F, rates 2 percent morn/day/nite.

• morn/day: 20 RATTATA, 21 RATTATA, 22 RATTATA, 22 RATTATA, 23 RATTATA, 24 RATTATA, 24 RATTATA
• nite: 20 GASTLY, 21 GASTLY, 22 GASTLY, 22 RATTATA, 23 RATTATA, 24 RATTATA, 24 RATTATA

Every floor 2F..9F carries the identical table (checked 2F at line 61 and 9F at line 257). The walkthrough only lists Rattata; Gastly at night is real.

---

TIN_TOWER_3F

• Script: maps/TinTower3F.asm; Blocks maps/TinTower3F.blk
• Header: data/maps/maps.asm:84; Dimensions constants/map_constants.asm:71 -> 10, 9 (group 3, map 6)

Warps

idx	x	y	destination map	dest warp
1	10	14	TIN_TOWER_2F	1
2	16	2	TIN_TOWER_4F	2

Object events

const	sprite	x	y	movement	type	script label	event flag
TINTOWER3F_POKE_BALL	SPRITE_POKE_BALL	3	14	STILL	OBJECTTYPE_ITEMBALL	TinTower3FFullHeal	EVENT_TIN_TOWER_3F_FULL_HEAL

Matches the walkthrough's "hop left for a Full Heal".

---

TIN_TOWER_4F

• Script: maps/TinTower4F.asm; Blocks maps/TinTower4F.blk
• Header: data/maps/maps.asm:85; Dimensions constants/map_constants.asm:72 -> 10, 9 (group 3, map 7)

Warps

idx	x	y	destination map	dest warp
1	2	4	TIN_TOWER_5F	2
2	16	2	TIN_TOWER_3F	2
3	2	14	TIN_TOWER_5F	3
4	17	15	TIN_TOWER_5F	4

BG events

x	y	type	script/item
11	6	BGEVENT_ITEM	TinTower4FHiddenMaxPotion -> hiddenitem MAX_POTION, EVENT_TIN_TOWER_4F_HIDDEN_MAX_POTION

Object events

const	sprite	x	y	movement	type	script label	event flag
TINTOWER4F_POKE_BALL1	SPRITE_POKE_BALL	14	10	STILL	OBJECTTYPE_ITEMBALL	TinTower4FUltraBall (42:4cc1)	EVENT_TIN_TOWER_4F_ULTRA_BALL
TINTOWER4F_POKE_BALL2	SPRITE_POKE_BALL	17	14	STILL	OBJECTTYPE_ITEMBALL	TinTower4FSuperPotion	EVENT_TIN_TOWER_4F_SUPER_POTION
TINTOWER4F_POKE_BALL3	SPRITE_POKE_BALL	2	12	STILL	OBJECTTYPE_ITEMBALL	TinTower4FEscapeRope	EVENT_TIN_TOWER_4F_ESCAPE_ROPE

---

TIN_TOWER_5F

• Script: maps/TinTower5F.asm; Blocks maps/TinTower5F.blk
• Header: data/maps/maps.asm:86; Dimensions constants/map_constants.asm:73 -> 10, 9 (group 3, map 8)

Warps

idx	x	y	destination map	dest warp
1	11	15	TIN_TOWER_6F	2
2	2	4	TIN_TOWER_4F	1
3	2	14	TIN_TOWER_4F	3
4	17	15	TIN_TOWER_4F	4

BG events

x	y	type	script/item
16	14	BGEVENT_ITEM	TinTower5FHiddenFullRestore -> hiddenitem FULL_RESTORE, EVENT_TIN_TOWER_5F_HIDDEN_FULL_RESTORE
3	15	BGEVENT_ITEM	TinTower5FHiddenCarbos -> hiddenitem CARBOS, EVENT_TIN_TOWER_5F_HIDDEN_CARBOS

Object events

const	sprite	x	y	movement	type	script label	event flag
TINTOWER5F_POKE_BALL	SPRITE_POKE_BALL	9	9	STILL	OBJECTTYPE_ITEMBALL	TinTower5FRareCandy (42:4d12)	EVENT_TIN_TOWER_5F_RARE_CANDY

---

TIN_TOWER_6F

• Script: maps/TinTower6F.asm - warps only, no items, no objects
• Blocks: maps/TinTower6F.blk
• Header: data/maps/maps.asm:87; Dimensions constants/map_constants.asm:74 -> 10, 9 (group 3, map 9)

Warps

idx	x	y	destination map	dest warp
1	3	9	TIN_TOWER_7F	1
2	11	15	TIN_TOWER_5F	1

The walkthrough's "go up and you'll get a Max Potion ... left across the upper bridge to get a Full Heal" floor has no item balls and no bg events at all in pokegold. See Unresolved.

---

TIN_TOWER_7F

• Script: maps/TinTower7F.asm; Blocks maps/TinTower7F.blk
• Header: data/maps/maps.asm:88; Dimensions constants/map_constants.asm:75 -> 10, 9 (group 3, map 10)

Warps

idx	x	y	destination map	dest warp
1	3	9	TIN_TOWER_6F	1
2	10	15	TIN_TOWER_8F	1
3	12	7	TIN_TOWER_7F	4
4	8	3	TIN_TOWER_7F	3
5	6	9	TIN_TOWER_9F	5

Warps 3/4 are the in-floor pair the walkthrough calls "go through the next two warps".

Object events

const	sprite	x	y	movement	type	script label	event flag
TINTOWER7F_POKE_BALL	SPRITE_POKE_BALL	16	1	STILL	OBJECTTYPE_ITEMBALL	TinTower7FMaxRevive	EVENT_TIN_TOWER_7F_MAX_REVIVE

---

TIN_TOWER_8F

• Script: maps/TinTower8F.asm; Blocks maps/TinTower8F.blk
• Header: data/maps/maps.asm:89; Dimensions constants/map_constants.asm:76 -> 10, 9 (group 3, map 11)

Warps

idx	x	y	destination map	dest warp
1	2	5	TIN_TOWER_7F	2
2	2	11	TIN_TOWER_9F	1
3	16	7	TIN_TOWER_9F	2
4	10	3	TIN_TOWER_9F	3
5	14	15	TIN_TOWER_9F	6
6	6	9	TIN_TOWER_9F	7

Object events

const	sprite	x	y	movement	type	script label	event flag
TINTOWER8F_POKE_BALL1	SPRITE_POKE_BALL	7	13	STILL	OBJECTTYPE_ITEMBALL	TinTower8FNugget	EVENT_TIN_TOWER_8F_NUGGET
TINTOWER8F_POKE_BALL2	SPRITE_POKE_BALL	11	6	STILL	OBJECTTYPE_ITEMBALL	TinTower8FMaxElixer	EVENT_TIN_TOWER_8F_MAX_ELIXER
TINTOWER8F_POKE_BALL3	SPRITE_POKE_BALL	3	1	STILL	OBJECTTYPE_ITEMBALL	TinTower8FFullRestore	EVENT_TIN_TOWER_8F_FULL_RESTORE

---

TIN_TOWER_9F

• Script: maps/TinTower9F.asm (42:4de0 TinTower9F_MapScripts) - no callbacks, no objects; carries two unreferenced texts TinTower9FUnusedHoOhText / TinTower9FUnusedLugiaText
• Blocks: maps/TinTower9F.blk (2b:625f)
• Header: data/maps/maps.asm:90; Dimensions constants/map_constants.asm:77 -> 10, 9 (group 3, map 12)

Warps

idx	x	y	destination map	dest warp
1	12	3	TIN_TOWER_8F	2
2	2	5	TIN_TOWER_8F	3
3	12	7	TIN_TOWER_8F	4
4	7	9	TIN_TOWER_ROOF	1
5	16	7	TIN_TOWER_7F	5
6	6	13	TIN_TOWER_8F	5
7	8	13	TIN_TOWER_8F	6

Warp 4 at (7, 9) is the only exit to the roof.

---

TIN_TOWER_ROOF

• Script: maps/TinTowerRoof.asm (5b:68ff callback, 5b:6913 TinTowerHoOh)
• Blocks: maps/TinTowerRoof.blk (2b:62b9)
• Header: data/maps/maps.asm:344 -> TILESET_TOWER, ROUTE, LANDMARK_TIN_TOWER, MUSIC_TIN_TOWER, phone FALSE, PALETTE_AUTO, FISHGROUP_SHORE
• Dimensions: constants/map_constants.asm:318 -> 10, 9, and note the group: TIN_TOWER_ROOF is map 12 of group 15 (FAST_SHIP), not group 3 with the rest of the tower.

Warps

idx	x	y	destination map	dest warp
1	9	13	TIN_TOWER_9F	4

Coord events: none. BG events: none.

Object events

const	sprite	x	y	movement	type	script label	event flag
TINTOWERROOF_HO_OH	SPRITE_HO_OH	9	5	SPRITEMOVEDATA_POKEMON	OBJECTTYPE_SCRIPT, palette PAL_NPC_RED	TinTowerHoOh	EVENT_TIN_TOWER_ROOF_HO_OH

Scripts of interest

• TinTowerRoofHoOhCallback - callback MAPCALLBACK_OBJECTS: checkevent EVENT_FOUGHT_HO_OH / iftrue .NoAppear, then checkitem RAINBOW_WING / iftrue .Appear. Same shape as Lugia's: the wing must be in the bag, not merely once-received.
• TinTowerHoOh (5b:6913) - text "Shaoooh!", cry HO_OH, pause 15, setevent EVENT_FOUGHT_HO_OH before the fight, checkver / iftrue .Silver.
  • Gold arm: loadwildmon HO_OH, 40.
  • .Silver: loadwildmon HO_OH, 70 - the level the walkthrough quotes.
  • Both arms run loadvar VAR_BATTLETYPE, BATTLETYPE_FORCEITEM first, and Ho-Oh's base row is db SACRED_ASH, SACRED_ASH (data/pokemon/base_stats/ho_oh.asm:9), so Ho-Oh always holds a SACRED_ASH. That is a guaranteed item a bot should strip before/after the catch.

Escape Rope caveat: EscapeRopeFunction -> .CheckCanDig (engine/events/overworld.asm:724-754) only succeeds when GetMapEnvironment is CAVE or DUNGEON. TIN_TOWER_ROOF is ROUTE, so the walkthrough is right that you must go back down to 9F first. Every Whirl Island map including WHIRL_ISLAND_LUGIA_CHAMBER is CAVE, so the rope works on the spot there.

Catch math: Ho-Oh's catch rate is also 3 (data/pokemon/base_stats/ho_oh.asm:7). Its dex weight is 4390 (data/pokemon/dex_entries/gold/ho_oh.asm) = 199 kg, which falls in the HeavyBallMultiplier "add 0" bracket - so unlike Lugia, a Heavy Ball is worse than an Ultra Ball on Ho-Oh.

---

3. Blockers and gates

Gate	Enforced by (file:label)	Requirement	Unlock condition
Reaching Route 41 at all	SurfFunction.TrySurf, engine/events/overworld.asm:322 (badge test at :340)	ENGINE_FOGBADGE + a party member that knows SURF	Fog Badge (Morty)
Whirlpools guarding the Whirl Islands	WhirlpoolFunction engine/events/overworld.asm:1061 (badge test at :1077) and TryWhirlpoolOW :1167 (badge test at :1171)	ENGINE_GLACIERBADGE + WHIRLPOOL in the party	Glacier Badge (Pryce, badge 7) - not eight badges, see Unresolved
Darkness inside every Whirl Island map	FlashFunction.CheckUseFlash, engine/events/overworld.asm:271	ENGINE_ZEPHYRBADGE + FLASH, and wTimeOfDayPalset == DARKNESS_PALSET (the map header's PALETTE_DARK)	Zephyr Badge. Flash is refused on any non-dark map, so a bot must only try it inside
Climbing back up the B2F waterfall	WaterfallFunction engine/events/overworld.asm:611 (badge test at :618) and TryWaterfallOW :683 (badge test at :687); direction check CheckMapCanWaterfall (must face UP, wTileUp is a waterfall tile)	ENGINE_RISINGBADGE + WATERFALL	Rising Badge (Clair). Descending needs nothing - only the UP direction is gated
B1F boulder at (23, 26)	WhirlIslandB1FBoulder -> jumpstd StrengthBoulderScript	STRENGTH + ENGINE_PLAINBADGE	optional; not on the Lugia path
Lugia not on the map	WhirlIslandLugiaChamberLugiaCallback	checkitem SILVER_WING true and EVENT_FOUGHT_LUGIA clear	EVENT_GOT_SILVER_WING via PewterCityGrampsScript (Gold) or RadioTower5F (Silver) - and keep the wing in the bag
Ho-Oh not on the map	TinTowerRoofHoOhCallback	checkitem RAINBOW_WING true and EVENT_FOUGHT_HO_OH clear	EVENT_GOT_RAINBOW_WING via RadioTower5F (Gold) or PewterCityGrampsScript .RainbowWing (Silver)
Tin Tower stairs to 2F	TinTower1F object row: sage stands on (10, 2), masked by EVENT_TEAM_ROCKET_DISBANDED	flag must be set	setevent EVENT_TEAM_ROCKET_DISBANDED in maps/RadioTower5F.asm:130 or maps/PewterCity.asm:51
Tin Tower entrance corridor	coord_event 4, 7 / 5, 7 under SCENE_ECRUTEAKTINTOWERENTRANCE_SAGE_BLOCKS	scene must be NOOP	maps/EcruteakGym.asm:34 setmapscene ... SCENE_ECRUTEAKTINTOWERENTRANCE_NOOP on the Fog Badge
One-shot mascot	Lugia / TinTowerHoOh set EVENT_FOUGHT_LUGIA / EVENT_FOUGHT_HO_OH before startbattle	n/a	none. Save-before-fight is the only recovery

---

4. Bot checklist

Preconditions for either branch: 8 Johto badges (Zephyr, Fog, Plain, Glacier, Rising in particular), party moves SURF, WHIRLPOOL, FLASH, WATERFALL (STRENGTH optional), the version-opposite wing in the bag, a stack of ULTRA_BALL (HEAVY_BALL for Lugia), and a save immediately before the mascot.

Gold branch - Lugia

#	Map	Target	Intent	Precondition	Postcondition
1	any	Olivine City	fly	ENGINE_FLYPOINT_OLIVINE	on OLIVINE_CITY
2	OLIVINE_CITY	west edge	walk, then surf	ENGINE_FOGBADGE + SURF	on ROUTE_40
3	ROUTE_40	south edge	surf	-	on ROUTE_41
4	ROUTE_41	any block id $07 (TILESET_JOHTO whirlpool)	face it, press A -> TryWhirlpoolOW	ENGINE_GLACIERBADGE + WHIRLPOOL	block replaced with $36 for this map session only (DisappearWhirlpool writes the map buffer, not the save)
5	ROUTE_41	(36, 19) warp 2	walk onto	whirlpools cleared	on WHIRL_ISLAND_NE at (3, 13)
6	WHIRL_ISLAND_NE	menu	use FLASH	ENGINE_ZEPHYRBADGE, map palette PALETTE_DARK	cave lit
7	WHIRL_ISLAND_NE	object WHIRLISLANDNE_POKE_BALL (11, 11)	walk onto / A	EVENT_WHIRL_ISLAND_NE_ULTRA_BALL clear	ULTRA_BALL in bag, flag set
8	WHIRL_ISLAND_NE	warp 2 (17, 3) (or warp 3 (13, 11))	walk onto	-	WHIRL_ISLAND_B1F (35, 3) / (29, 9)
9	WHIRL_ISLAND_B1F	(19, 26)	pick up	EVENT_WHIRL_ISLAND_B1F_ESCAPE_ROPE clear	ESCAPE_ROPE in bag
10	WHIRL_ISLAND_B1F	(33, 23)	pick up	EVENT_WHIRL_ISLAND_B1F_CALCIUM clear	CALCIUM in bag
11	WHIRL_ISLAND_B1F	optional (30, 4), (36, 18), (2, 23)	face + A (hidden)	matching EVENT_..._HIDDEN_* clear	Rare Candy / Ultra Ball / Full Restore
12	WHIRL_ISLAND_B1F	warp 4 (9, 31) or warp 5 (23, 31)	walk onto	-	WHIRL_ISLAND_SW
13	WHIRL_ISLAND_SW	(15, 2)	pick up	EVENT_WHIRL_ISLAND_SW_GUARD_SPEC clear	GUARD_SPEC in bag
14	WHIRL_ISLAND_B1F	warp 7 (25, 21)	walk onto	-	WHIRL_ISLAND_B2F (11, 5)
15	WHIRL_ISLAND_B2F	(6, 4)	pick up	EVENT_WHIRL_ISLAND_B2F_MAX_REVIVE clear	MAX_REVIVE in bag
16	WHIRL_ISLAND_B2F	waterfall block, moving DOWN	surf south over it	SURF only (no badge for descent)	lower B2F pool
17	WHIRL_ISLAND_B2F	warp 3 (7, 25)	walk onto	-	WHIRL_ISLAND_LUGIA_CHAMBER (9, 13)
18	WHIRL_ISLAND_LUGIA_CHAMBER	-	SAVE	-	recoverable
19	WHIRL_ISLAND_LUGIA_CHAMBER	object at (9, 5)	surf north, A	SILVER_WING in bag, EVENT_FOUGHT_LUGIA clear	EVENT_FOUGHT_LUGIA set, wild Lugia Lv70 (Gold) / Lv40 (Silver)
20	battle	-	weaken, status, throw balls	catch rate 3 (Ultra 6, Heavy 23)	Lugia caught, disappear + reloadmapafterbattle
21	WHIRL_ISLAND_LUGIA_CHAMBER	bag	use ESCAPE_ROPE	environment CAVE	back at last Pokecenter spawn

Silver branch - Ho-Oh

#	Map	Target	Intent	Precondition	Postcondition
1	any	Ecruteak City	fly	ENGINE_FLYPOINT_ECRUTEAK	on ECRUTEAK_CITY
2	ECRUTEAK_CITY	warp 3 (18, 11)	walk onto	-	ECRUTEAK_TIN_TOWER_ENTRANCE (4, 17)
3	ECRUTEAK_TIN_TOWER_ENTRANCE	(4, 7) / (5, 7)	walk through	map scene must be NOOP (Fog Badge)	no coord event fires
4	ECRUTEAK_TIN_TOWER_ENTRANCE	warp 3 (5, 3)	walk onto	-	same map, (17, 15)
5	ECRUTEAK_TIN_TOWER_ENTRANCE	warp 5 (17, 3)	walk onto	-	ECRUTEAK_TIN_TOWER_BACK_ENTRANCE (2, 4)
6	ECRUTEAK_TIN_TOWER_BACK_ENTRANCE	warp 1 (7, 4)	walk onto	-	ECRUTEAK_CITY (20, 2)
7	ECRUTEAK_CITY	warp 12 (37, 7)	walk east then onto	-	TIN_TOWER_1F (9, 15)
8	TIN_TOWER_1F	warp 3 (10, 2)	walk onto	EVENT_TEAM_ROCKET_DISBANDED set (sage masked)	TIN_TOWER_2F (10, 2)
9	TIN_TOWER_2F	warp 1 (10, 14)	walk onto	-	TIN_TOWER_3F
10	TIN_TOWER_3F	(3, 14) then warp 2 (16, 2)	pick up, walk onto	EVENT_TIN_TOWER_3F_FULL_HEAL clear	FULL_HEAL; TIN_TOWER_4F
11	TIN_TOWER_4F	(14, 10), (17, 14), (2, 12), hidden (11, 6)	pick up	matching flags clear	Ultra Ball, Super Potion, Escape Rope, hidden Max Potion
12	TIN_TOWER_4F	warp 1 (2, 4) / 3 (2, 14) / 4 (17, 15)	walk onto	-	TIN_TOWER_5F
13	TIN_TOWER_5F	(9, 9), hidden (16, 14) and (3, 15)	pick up	matching flags clear	Rare Candy, Full Restore, Carbos
14	TIN_TOWER_5F	warp 1 (11, 15)	walk onto	-	TIN_TOWER_6F (11, 15)
15	TIN_TOWER_6F	warp 1 (3, 9)	walk onto	-	TIN_TOWER_7F (3, 9)
16	TIN_TOWER_7F	(16, 1); warps 3 (12, 7) / 4 (8, 3)	pick up, hop the pair	EVENT_TIN_TOWER_7F_MAX_REVIVE clear	MAX_REVIVE
17	TIN_TOWER_7F	warp 2 (10, 15)	walk onto	-	TIN_TOWER_8F (2, 5)
18	TIN_TOWER_8F	(7, 13), (11, 6), (3, 1)	pick up	matching flags clear	Nugget, Max Elixer, Full Restore
19	TIN_TOWER_8F	warp 2 (2, 11) (or 3/4/5/6)	walk onto	-	TIN_TOWER_9F
20	TIN_TOWER_9F	warp 4 (7, 9)	walk onto	-	TIN_TOWER_ROOF (9, 13)
21	TIN_TOWER_ROOF	-	SAVE	-	recoverable
22	TIN_TOWER_ROOF	object at (9, 5)	walk up, A	RAINBOW_WING in bag, EVENT_FOUGHT_HO_OH clear	EVENT_FOUGHT_HO_OH set, wild Ho-Oh Lv70 (Silver) / Lv40 (Gold) holding SACRED_ASH
23	battle	-	weaken, status, Ultra Balls	catch rate 3; Heavy Ball gives no bonus here	Ho-Oh caught
24	TIN_TOWER_9F	warp 1 on the roof, then bag	descend, use ESCAPE_ROPE	roof is ROUTE environment - rope fails there	back at spawn

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5. Port coverage

Beat	Port file	Status
Map headers, warps, coord/bg/object events for all of these maps	src/import/RomExtractorGen2.lua (walks all 26 map groups, MAP_GROUP_COUNT at line 47), consumed by src/world/gen2/Map.lua / World.lua	implemented (generic - no map-specific code, so these maps come in with everything else)
MAPCALLBACK_OBJECTS (the Lugia / Ho-Oh appear-check)	src/world/gen2/World.lua:5700 runMapCallback("MAPCALLBACK_OBJECTS"); regression driver tests/drivers/gold_map_callbacks.lua	implemented
Object masking by event flag (CheckObjectFlag) - the Tin Tower 1F sage, every item ball	src/world/gen2/World.lua:5106,5122 events:objectVisible(obj.eventFlag)	implemented
checkver version split (Lv70 vs Lv40 mascot)	src/script/gen2/Vm.lua:774-783; opcode table src/script/gen2/Opcodes.lua:29	implemented (comments even cite WhirlIslandLugiaChamber by name)
loadwildmon / startbattle / reloadmapafterbattle	src/script/gen2/Opcodes.lua:98-101, src/script/gen2/Vm.lua:817-896	implemented
BATTLETYPE_FORCEITEM -> Ho-Oh's guaranteed SACRED_ASH	src/world/gen2/World.lua:107-111 and :4571-4579	implemented
Whirlpool field move, badge gate and block replacement	src/world/gen2/FieldMoves.lua:109 (WHIRLPOOL = "GLACIER"), :219 WHIRLPOOL_BLOCKS, :247 somethingToWhirlpool, :542 whirlpoolFromMenu, :626 tryWhirlpoolOW	implemented
Flash + PALETTE_DARK darkness	src/world/gen2/FieldMoves.lua:105,468; src/world/gen2/Palettes.lua:53,75-103	implemented
Waterfall (up-only gate, RISINGBADGE)	src/world/gen2/FieldMoves.lua:110,258,646	implemented
Hidden items (hiddenitem bg events)	src/world/gen2/HiddenItems.lua, src/world/gen2/World.lua:1373,5286	implemented
Catch rate formula incl. the two cart bugs	src/battle/gen2/Catching.lua:1-90	implemented
Heavy Ball weight bonus (the FAQ's Lugia tip)	src/battle/gen2/Catching.lua:36 - HEAVY_BALL = 1, a flat multiplier with a comment saying the specialty balls "key off conditions the caller supplies", and no dex-weight lookup anywhere	missing - a Heavy Ball currently behaves as a plain Poke Ball on Lugia
Magnet Train hop that opens the section	src/core/gen2/MagnetTrain.lua	implemented (not re-verified for this section)
Escape Rope environment check (CAVE/DUNGEON only, roof excluded)	not located in src/world/gen2/ or src/battle/gen2/ by grep	unverified - could not find an EscapeRopeFunction equivalent; a bot should not assume the roof refusal is modelled
Hand-ported scripts for these specific maps	none - grep for whirl/tintower/lugia/hooh across src/ returns only battle-anim and title-screen hits	not applicable (all script bodies are extracted, run through src/script/gen2/Vm.lua)

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6. Unresolved / verify by hand

1. "You'll need eight badges in order to use Whirlpool." The asm gates Whirlpool on ENGINE_GLACIERBADGE alone (engine/events/overworld.asm:1077 and :1171), i.e. seven badges. Eight is wrong, though harmless in practice for a post-game section.
2. Whirl Islands item list. The FAQ lists Calcium, Escape Rope, Guard Specs, Max Revive x2, Ultra Ball. The asm has one Max Revive in the entire dungeon (WhirlIslandB2FMaxRevive at B2F (6, 4)) and additionally a FULL_RESTORE, CARBOS, NUGGET on B1F, a second FULL_RESTORE and a MAX_ELIXER on B2F, plus three hidden items on B1F that the FAQ never mentions. The walkthrough's two "grab the Max Revive" beats cannot both be the B2F ball; the first one is unlocatable.
3. Tin Tower item list. The FAQ names a PP Up, an HP Up, a Max Potion item ball, and a second Full Heal. None exist in pokegold: there is no PP_UP or HP_UP anywhere in maps/TinTower*.asm, the only Max Potion is the hidden TinTower4FHiddenMaxPotion at (11, 6), and the only Full Heal is TinTower3FFullHeal. Conversely the FAQ omits SUPER_POTION (4F), NUGGET/FULL_RESTORE (8F) and the three hidden items on 4F/5F. The list looks like it was written against a different version of the game.
4. "On the next level, go up and you'll get a Max Potion ... Full Heal" places two items on the 6F-shaped floor; maps/TinTower6F.asm has an empty def_bg_events and an empty def_object_events. Not locatable.
5. Ho-Oh's moveset. The FAQ says "Safeguard and Ancient Power ..., Punishment, and Sacred Fire". PUNISHMENT does not exist in Gen 2 at all (data/pokemon/evos_attacks.asm:3324-3336 is the whole learnset). Derived from that table plus FillMoves (engine/pokemon/evolve.asm:478, which keeps the last four moves learnable at or below the level), a level-70 Ho-Oh should have RECOVER, FIRE_BLAST, SUNNY_DAY, SWIFT, and a level-40 one SACRED_FIRE, SAFEGUARD, GUST, RECOVER. Worth confirming in-engine before a bot plans around Sacred Fire; the FillMoves derivation is mine, not a literal table in the asm.
6. Lugia's Pokemon list at the Whirl Islands. The FAQ lists Zubat, Seel, Krabby, Horsea, Seadra and omits GOLBAT (in every grass slot 5), TENTACOOL / TENTACRUEL (SW and B2F water). Seadra only appears in WHIRL_ISLAND_LUGIA_CHAMBER's water table.
7. "Swimmer Kara" as a whirlpool landmark. Her object is at (44, 28) on Route 41; the whirlpool "just northwest" of her is a .blk block, not an event, so the exact coordinate could not be pinned from the asm text. A bot must scan maps/Route41.blk for TILESET_JOHTO block $07.
8. The Whirl Islands ledge/jump routing ("leap the ledge to the right on that bike", "two items on the cliff but you can't reach those") is entirely block and collision data in maps/WhirlIsland*.blk. None of it is expressible from the event tables; a bot needs the decoded block/collision grid.
9. The Tin Tower jump-platform routing (the long "left x5, down, right x2 ..." sequences) is likewise .blk data. Only the warp endpoints above are asm facts.
10. "go into the Bell Tower entry house" - the map, the sign and every text string in pokegold call it TIN TOWER (TinTowerSign, EcruteakTinTowerEntranceSageText). "Bell Tower" is the post-GS rename.
11. Escape Rope on the port. Could not find the port's equivalent of EscapeRopeFunction's CAVE/DUNGEON environment check, so I cannot say whether the port correctly refuses the rope on TIN_TOWER_ROOF.