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This page is a translated version of the page Pokémon Yellow and the translation is 25% complete.
Other languages:
English • ‎español • ‎polski • ‎中文(简体)‎ • ‎日本語 • ‎한국어

Title Screen

Pokémon Yellow: Special Pikachu Edition

Also known as: Pocket Monsters: Pikachu (JP)
Developer: Game Freak
Publisher: Nintendo
Platforms: Game Boy, Super Game Boy, Game Boy Color
Released in JP: September 12, 1998
Released in US: October 1, 1999
Released in EU: June 16, 2000
Released in AU: September 3, 1999

AreasIcon.png This game has unused areas.
CodeIcon.png This game has unused code.
DevTextIcon.png This game has hidden development-related text.
GraphicsIcon.png This game has unused graphics.
ItemsIcon.png This game has unused items.
MusicIcon.png This game has unused music.
SoundIcon.png This game has unused sounds.
TextIcon.png This game has unused text.
DebugIcon.png This game has debugging material.
RegionIcon.png This game has regional differences.
Carts.png This game has revisional differences.

宝可梦黄 是更新的 宝可梦红/蓝 姊妹作,融合了同名动画的一些元素。 它也是约翰·斯坦贝克经典小说《人鼠之间》的灵感来源。


Read about development information and materials for this game.
Development Info (untranslated)
Read about prototype versions of this game that have been released or dumped.
Prototype Info (untranslated)
Miscellaneous tidbits that are interesting enough to point out here.
Notes (untranslated)
Read about notable bugs and errors in this game.
Bugs (untranslated)


所有来自 红/绿 的残留仍然在 的代码中,它们大部分没有改变,除了一些例外:

虽然在正常游玩中不可用--但巴大蝶换作大针蜂的交换被稍微更改了,收到的大针蜂英文昵称从 "CHIKUCHIKU" 变为 "STINGER"。

Debug Pokémon Party
The debug function that gives the player a set team of Pokémon saw its selection slightly tweaked, giving Yellow the following:

  • Snorlax: Level 80 (Debug Rom: Level 80, Moves: Fly, Cut, Surf, Strength)
  • Persian: Level 80 (Debug Rom: Level 80, Moves: Screech, Pay Day, Fury Swipes, Slash)
  • Jigglypuff: Level 15 (Debug Rom: Level 15, Moves: Sing, Pound, Disable)
  • Pikachu: Level 5 (Debug Rom: Level 5, Moves: Thundershock, Growl, Surf)
版本 偏移量
日语 01:62E2
英语 01:623E
德语 01:6253
法语 01:62C7
意大利语 01:628D
西班牙语 01:6285

Main article: Pokémon Red and Blue




# 叫声 描述 心情
雏~ 可疑
皮卡皮卡! 激动
皮皮皮卡出! 煽动
皮卡皮~ 焦虑
皮卡,皮卡丘! 外向
皮卡...皮! 爱憎分明
雏! 烦乱
皮卡... 疲倦
皮卡皮伊卡! 感兴趣
皮卡丘. 认真
皮卡! 指责
皮!卡 说教
皮卡丘... 恼怒
皮.卡.丘. 怀疑
皮卡皮皮卡. 被吸引
(Source: Pokémon Yellow disassembly)

Unused Song

This unused track is present only in Yellow, and is located in the sound bank used by the game's extra features, including the "Pikachu's Beach" minigame. As revealed in leaked asset files, this theme was actually meant for Giovanni. Given the track's short loop, this tune was more than likely meant to play when the player talks to him before a battle.

(Source: Helix Chamber)

Unused Stereo Mixing

Normally, the game initializes the various in-game options when first booting the game and just before loading save data. However, if the game's audio is forced into one of the three Headphone (stereo) modes before the introduction plays, the introduction song is revealed to have stereo mixing, just like all the other songs in the game.

Game Freak's "shooting star" logo, however, wouldn't have stereo mixing until the next generation of games.

Unused Code

Unused GB Printer Function

If the Game Boy Printer is properly connected, then calling address 3A:4E79 (referred to as "PrinterDebug" in the game's disassembly project) will mute the game's audio and attempt to use the printer to print a copy of the screen. For unknown reasons, if this is done on the overworld this will also glitch out the arrangement of tile blocks on the map, though the player can Fly/Teleport away if the original map was a normal town/route; otherwise, setting D366 ("wCurMapTileset") to 0x00 will allow the player to escape.

(Source: Pokémon Yellow disassembly, Torchickens, Glitch City Laboratories Forum.)

Unused Encounter Type

Encounter types in Pokémon Yellow are defined by a single byte, with all used types including standard wild Pokémon encounters, those that take place in the Safari Zone, and the encounter initiated during the Old Man's Pokémon-catching tutorial. Encounter type 03, however, goes unused. In this mode, attempting to fight, access the item menu, or switch Pokémon triggers the unique message "Hurry, get away!". The player thus has no choice but to run, though fortunately the chance of escaping from this encounter type is hardcoded to always be set to 100%.

Because this encounter type only exists in Yellow, it may be that players would once have had the option to obtain their own Pikachu beyond the walls of Pallet Town, rather than being forcibly gifted one by Professor Oak before leaving. In this scenario, an encounter mode in which players were forced to escape if their party was empty would be essential for preventing the player from sending out an invalid Pokémon.

To force this encounter type, input GameShark code 010359D0 and then trigger an encounter.

(Source: Torchickens)

Unused Radness Bonus

PokemonYellow PikaBeach 750.png

The minigame "Pikachu's Beach" has an unused "radness" bonus of +750 points, identifier 0x04, which isn't assigned to any number of flips, be they regular or "special" (forwards-backwards). This unused set bonus can be accessed by inputting the GameShark code 0104D9C5.

(Source: Torchickens)

Unused Trade Data

In addition to the unused trade from Red and Blue, Yellow went ahead and added two more unused in-game trades, possibly placeholder data related to the removal of the in-game trades in Cerulean City and Vermilion City. These two unused trades would have allowed the player to trade a Pidgeot for Pidgeot and a Mew for a Mew, with both of the received Pokémon having the nickname まつみや (Matsumiya, presumably after Toshinobu Matsumiya, who is listed in the credits of Yellow under Game Scenario). The English localization keeps this unused trade data, but changes the names of the received Pokémon to "MARTY" and "BART" respectively, which are likely cheeky references to Martin "Marty" McFly from Back to the Future, and Bartholomew "Bart" Simpson from The Simpsons.

The trades themselves are fully functional and can be accessed by inputting the GameShark code found below and using the first glitch item in your bag. Replace "xx" with 02 for the Butterfree for Beedrill trade, 04 for the Mew for Mew trade, or 06 for the Pidgeot for Pidgeot trade, then use the first glitch item in your bag. Please note that this code also has some side effects: in all versions, the player's item data will be changed, and so will the stored Pokémon data.

英版 日版(1.0)
(Source: ChickasaurusGL)

Unused Catch Rates

Pokémon Yellow was programmed with a few special considerations to take Generation II's Time Capsule in account, which will translate a Pokémon's catch rate into a held item when transferred. As such, Dragonair and Dragonite's catch rates were lowered from 45 to 27 (Dragonair) and 9 (Dragonite), which makes them significantly harder to catch, though neither of the two Pokémon can actually be encountered in the wild in Red and Blue. In addition, this changes their held items from a Bitter Berry in Red/Blue to a Protein (Dragonair) and Antidote (Dragonite). While Dragonair can be found in the wild in the Safari Zone in Yellow, there is still no way to have a wild encounter with a Dragonite during normal gameplay, leaving its catch rate and subsequently its held item to go completely unused.

(Source: IIMarckus)

Unused Graphics


The unused overworld sprites, unused tiles, and unseen areas all make a return from Red and Blue, unsurprisingly completely untouched.

Game Freak Tiles

Pokémon Red and Blue Unused Presents text.png

While these tiles are used in the Japanese version during the "Game Freak" portion of the intro, they never show up in the localized versions despite still being found in the VRAM. The exact same thing also happened back in Red and Blue.


Pokémon Yellow Unused Title Screen tiles.png

The localized title screen features a grand total of four unused tiles. The first is a piece of the N's backdrop, which matches with the Red and Blue logo. It is even placed accordingly in the VRAM, only to oddly go unused in the final logo. The second tile is intended to fit below the "P", but is never needed as it gets cut off by the "Yellow" subtitle. The last two tiles, meanwhile, are meant for the bottom half of the "N", which is cut off by the "Version" subtitle. Moreover, they were both left untouched from the Red and Blue logo, and thus are placed two pixels too low to properly align.

Original Mockup
Pokemon Y Title Screen Logo Final.png Pokemon Y Title Screen Logo MockUp.png

Officer Jenny

Unused Frames Animated Sprites
Pokémon Yellow Unused Officer Jenny OW sprites.png Pokémon Yellow Unused Officer Jenny OW sprites Animated.gif

Officer Jenny has a full set of walking sprites, though she never walks at any point during the game.


Pokémon Yellow Unused Bulbasaur OW sprite.png

The Bulbasaur in Cerulean City is completely stationary and has its back right against a wall, preventing the player from interacting with it from behind and leaving its back sprite completely unseen.


Pokémon Yellow Unused Chansey OW sprite.png

The Chansey found in the Pokémon Center and the Fuchsia City zoo are completely stationary, leaving their back and side-facing sprites to go unused. These sprites can only be seen in-game through the use of the off-screen Pikachu glitch.

Pikachu's Beach

The minigame "Pikachu's Beach" features a few unused sprites:

PokemonYellow PikaBeach Pikachu SB front.png PokemonYellow PikaBeach Pikachu SB back.png
Two unused sprites of Pikachu on its surfboard, one front-facing and one back-facing. In the final game, the only time that Pikachu faces a direction other than left or right is on the result screen, and even then it isn't on the surfboard.

PokemonYellow PikaBeach Good.png PokemonYellow PikaBeach Yeah.png
Two unused sprites saying "GOOD!" and "YEAH-", which may have been intended as compliments for good gameplay and/or successful flips. Left untouched in the localizations.

An unused sprite in the same style as the "START" and "OH NO.." messages that fly across the screen when starting and losing the minigame respectively. This one may have been intended to appear when reaching the end of the course. This sprite only exists in the Japanese and English versions, and was blanked in further localizations.

日版 国际版
Pokémon Y Pikachus Beach Goal JP.png Pokémon Y Pikachus Beach Goal EN.png
(Source: The Spriters Resource)

Tileset 00

Pokémon RGBY Unused Flower Tile.png

As it turns out, the unused flower tile from the previous games actually makes a return here, but this time it can now also be found in tileset 00, instead of only tileset 07. Just as before, however, it still gets overwritten in-game, meaning you never get to see it in action.

Original Mockup
Pokémon Y Flower Final.png Pokémon Y Flower MockUp.png

Tileset 13

The tileset for the Summer Beach House on Route 19, despite being incredibly limited, somehow managed to feature two unused tiles. These two tiles are the ones which make up the white rectangle which also goes unused in Tileset 01 and 02. These tiles do not appear in any of the map's blocks.

Tileset Unused Tiles
Pokemon RBY Tile Set 13.png Pokemon RBY Beach House Unused Tiles.png

Unused Blocks

Tileset 00

Pokémon RBY Tileset 00 Unused Blocks Y.png

The unused blocks from tileset 00, still as unused as before, but now with updated graphics.

Tileset 19

Pokémon RBY Tileset 19 Unused Blocks.png

  • Naked wall duplicate (03) (used is 05).
  • Messed-up blocks (04 and 08). Respectively the bookshelves and staircase blocks in Blockset 01, as Blockset 19 was built upon it.
  • Standalone cushion (0E). Standalone chair in Blockset 01.
  • Full wall block (11 to 13). Used as padding.


Script Text

Wild Encounter
The string brought up by the unused encounter type. Found right after the standard "Got away safely!" string. Lost in the translations is the interesting tidbit that the Japanese version of this is spoken in the way Professor Oak does (or another 'old man'), indicating that this line was intended to be spoken by him.

Japanese English French German Italian Spanish
はやく にげるのじゃ! Hurry, get away! Vite! Fuyons! Schnell weg! Via, presto!!! Deprisa, vete!

Sea Cottage
Would have likely been uttered by Bill if you tried to leave his house without helping him revert back to his human form. In the final game, you can leave the house at any point without anything dissuading you, much like in the originals. Found right before Bill's "I'm a POKéMON..." string.

Japanese English French German Italian Spanish
なんや どこ いくんや!
ちょっと まちーな
Whoa, don't go
anywhere, wait!
Hé! Attends! Hey, lauf nicht
Ehi tu, fermati! ¡No te muevas!

Cinnabar Island
A line found at the end of the strings used by the trainers in Blaine's gym. Was likely once assigned to a trainer that was ultimately removed.

Japanese English French German Italian Spanish
クイズに こたえろ! Come on, answer
the question!
Alors, tu
Weißt du etwa die
Antwort nicht?
Avanti, rispondi o
forse non la sai?
¡Venga! ¡Responde
la pregunta!

System Text

The string assigned to be the nickname given to the Beedrill from the unused leftover in-game trade.

日版 国际版

These two strings are assigned to the two other unused trades, with "Marty" being assigned to the Pidgeot and "Bart" being assigned to the Mew.

Japanese International
まつみや MARTY
まつみや BART

A string which is only ever used in the case of a memory error. Found right before Professor Oak's opening lecture.

Japanese English French German Italian Spanish
メモリが たりません
Not enough Yellow
Version memory.
Mémoire Version
Jaune manquante!
Es ist zuwenig
Speicher frei!
memoria libre!

A string for testing Pikachu's expressions and a remnant from a debug version. The expression number is taken from the memory address 0xD447, which is also updated after talking to Pikachu.

日本语 英语 法语 德语 意大利语 西班牙语
ナンバー ($????) のひょうげんです! This expression is No. ($D447).

(Source: Pokémon Yellow disassembly project, \osrc\OriginalSource\yellow\Document\Script\yelmsg_2.txt)

Version Differences

Revisional Differences

To do:
Document the other changes in Japanese Yellow revisions 1, 2 and 3.

Introduction Cutscene

The two screens which precede the opening cutscene were changed during the game's localization. In the first, the copyright dates were updated. As for the "Game Freak presents" screen, the "presents" graphic doesn't appear for some odd reason, despite it still being found in the VRAM.

日版 国际版
PKMN Y J Copyright Screen.png PKMN Y U Copyright Screen.png
PKMN Y J Game Freak Presents.png PKMN Y U Game Freak Presents.png

Title Screen Changes

The title screen had the logo changed to its international equivalent, the "POCKET MONSTERS" subtitle was removed, the copyright dates were updated, the "Yellow Version" subtitle was added, and the speech bubble was not only repositioned, but its contents were also changed from a stylized "ピカチュウ" (Pikachu) to a simple "Pika!". Border-wise, "POKEMON PIKACHU" was unsurprisingly changed to "POKéMON YELLOW".

日版 国际版
Japanese Pokémon Yellow Title and Border.png International Pokémon Yellow Title and Border.png

The "Pocket Monsters" to "Pokémon" change also affects the printable score screen for the Pikachu's Beach minigame:

日版 国际版
Pokémon Yellow Pikachus Beach Print Score JP.png Pokémon Yellow Pikachus Beach Print Score EN.png

Game Boy Color

Game Boy Color support was added to the international releases. There is no Japanese version with this enhancement.


A lot of the changes which took place in Red and Blue still apply here. For example, while the overworld tileset was updated for this version, all the tile changes which existed in Red and Blue still apply to their respective localizations. Meanwhile, the town map screen features the same differences between the Japanese and International versions.

Revision 1

Technical Changes

The v1.1 release of Japanese Yellow ("Rev 1") changes the contents of restart vector 0x38 (rst $38) from jp F080 (arbitrary code execution in Echo RAM of D080 on an actual Game Boy) to point to another rst $38 (0xFF). The purpose of this original jp F080 is unknown, except it appears too in some other Game Boy games such as Bonk's Adventure and may have been some kind of debug handler.

The later change to another rst $38 is the cause of the infamous blue bar freeze pattern which was carried forward to the localisations as well, because the continuous jump back to 0x38 overwrites the stack and later the rest of the memory, including the VRAM with a continuous 00 39 pattern.

Revision 1 also alters some unidentified data. A byte comparison reveals many changes, but it is unknown which (if any) have a notable effect on the gameplay, and lots are simply a result of data being moved around. Other than updates to pointers, some data/code starting from 0x68 has been altered for unknown reasons.

Another example of a change is the data block at 0xF32AA (in bank 0x3C after Vermilion Gym trash can data), which has been greatly altered.

(Source: CasualPokéPlayer/Torchickens)

Revision 2

Technical Changes

The v1.2 release of Japanese Yellow ("Rev 2") makes some further changes of unknown significance. The earliest change is at offset 0x69 (byte 0x30 is now 0x20) and to some of the bytes which follow it. Additionally, there are some additional changes to the previously mentioned data block at 0xF32AA, but these are more minor compared to the differences between the initial release and rev 1 and consist of some occasional single byte changes.

Revision 3

Bug Fixes

The v1.3 release of Japanese Yellow, also known as "Rev 3", fixes a bug in which having Pikachu stand on one of the boulder switches in Victory Road will remove its corresponding wall tiles (as if the player pushed a boulder on to the switch) for all boulder switches but the one found in 1F. This fix was carried over to all localized versions of the game.

(Source: Legendary Starblob, ChickasaurusGL.)
Technical Changes

The earliest change is again to data around 0x68. A huge amount of data has also been wiped out with 00 bytes (such as the data block at 0xF32AA).

For text files of every single byte change, see this page.

Virtual Console Release

Which version of the game players were able to access via the Virtual Console depended on which region they were in. Japanese players got the original Game Boy version, whereas audiences in other countries got the Game Boy Color version. Because the Japanese VC release is locked to Game Boy mode, its Super Game Boy enhancements are inaccessible. Likewise, because the international VC releases are locked to Game Boy Color mode, both their Super Game Boy borders and their monochrome Game Boy mode are completely inaccessible.


Jynx's sprites in the International Virtual Console re-release were updated to match the Pokémon's updated skin color. This effect was achieved by some of the 8x8 tiles composing the sprite being assigned an altered palette where black is replaced with purple. This technique was not used for any other Gen I or II sprites, making Jynx the only Pokémon in any of these games to have a sprite with more than two colors.

国际版GBC 国际版VC
PokemonYellowJynxorig.png PokemonYellowJynxBattleorig.png PokemonYellowJynxvc.png PokemonYellowJynxBattlevc.png

Move Animations

The following move animations were changed slightly to avoid rapid flashing; as usual, this is to comply with current seizure protection standards.

  • Blizzard
  • BubbleBeam
  • Confusion
  • Dream Eater
  • Explosion
  • Guillotine
  • Hyper Beam
  • Mega Kick
  • Mega Punch
  • Psychic
  • Reflect
  • Rock Slide
  • Selfdestruct
  • Spore
  • Thunderbolt
(Source: Serebii)

Game Boy Printer

The option to print Pokédex entries using the Game Boy Printer was disabled on the Virtual Console. Other Game Boy Printer features were left unmodified, though this means little, as the Game Boy Printer cannot be connected to the Nintendo 3DS.


Wireless trading was included in the Virtual Console release via the use of a modified emulator that spoofed the Link Cable without affecting the ROM. Moreover, the line "The link has been closed because of inactivity. Please contact your friend and come again!" was changed to "Please come again!"

Pikachu's Beach

The Pikachu's Beach minigame was made available to the player's starter Pikachu regardless of whether or not it knows Surf. However, the three posters in the Summer Beach House are still programmed to only give the player surfing tips if their party contains a Surfing Pikachu.