Pokémon Yellow is the updated companion game to Pokémon Red and Blue, which incorporates elements of the series' eponymous anime. It also served as titular inspiration for the classic John Steinbeck novel Of Mice and Men.

Sub-Pages#

Leftovers#

All the unused data from Red and Green and Blue remains in the code of Yellow, virtually all of it unchanged aside from a few exceptions, which are documented below:

Unused Trade
Despite remaining unavailable in regular gameplay, the unused Butterfree-for-Beedrill in-game trade was modified slightly, with the received Beedrill having its English nickname changed from "CHIKUCHIKU" to "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)

Main article: Pokémon Red and Blue

Unused Audio#

Unused Cries#

There are multiple unused voice clips for the player's starter Pikachu.

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.

Unused Stereo Mixing#

Watch on YouTubeNormally, 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.

未使用の鳴き声#

To do: Add more information, if necessary, and the tracks of the cries themselves.

There are multiple unused cries for Pikachu that are various voice types performed by Ihue Ohtani, the Japanese voice actress of Pikachu in the anime.

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.

未使用の交換#

To do: Replace the video with screenshots if needed.

In addition to the unused Butterfree-for-Beedrill in-game trade from Red and Blue, Yellow adds two more unused trades, probably related to the removal of the in-game trades in Cerulean City and Vermilion City: Pidgeot-for-Pidgeot and Mew-for-Mew, respectively. In the Japanese Yellow, both received Pokémon are nicknamed まつみや (Matsumiya, presumably after Toshinobu Matsumiya, who is listed in the credits of Yellow under Game Scenario).

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.

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.

Unused Graphics#

Leftovers#

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

Game Freak Tiles#

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.

Title Screen#

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

バーチャルコンソールのよる違い#

Wireless trading was included, but this was via a modified emulator spoofing the Link Cable and did not affect the ROM of the game. Additionally, due to different regions getting different versions of the game, the same applies to the Virtual Console release. Japan got the original Game Boy version, whereas everyone else got the Game Boy Color version. The Japanese release is locked in Game Boy mode, so Super Game Boy enhancements are inaccessible, and international versions are locked in Game Boy Color mode, so both the Super Game Boy borders and monochrome Game Boy mode are inaccessible.

ピカチュウのサマービーチ#

The Pikachu's Beach minigame is available to the player's starter Pikachu, instead of a Pikachu which knows the move Surf. However, the three posters in the Summer Beach House are still programmed to give surfing tips only if a Pikachu that knows Surf is in the party.

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.

Chansey#

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.

わざアニメーション#

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

• ふぶき
• バブルこうせん
• ねんりき
• ゆめくい
• だいばくはつ
• ハサミギロチン
• はかいこうせん
• メガトンキック
• メガトンパンチ
• サイコキネシス
• リフレクター
• いわなだれ
• じばく
• キノコのほうし
• １０まんボルト

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.

ルージュラ#

海外Game Boy Color	海外バーチャルコンソール

Exclusively in the International Pokémon Yellow Virtual Console releases, Jynx's sprites were altered to match its modern Western appearance. Since the Japanese Pocket Monsters: Pikachu is not Game Boy Color-enhanced, it was not affected by this change. Interestingly, through this change, Jynx now has more colors in its sprite than any other Pokémon in Yellow.

(Source: Serebii)

未使用のポケモン贈呈機能#

ポケモン 赤と緑は、ポケモンをプレイヤーの手持ちに追加するデバッグ機能があります。この機能はピカチュウ版にも提供されており、次のようなポケモンが追加されます:

• レベル 80 カビゴン
• レベル 80 ペルシアン
• レベル 15 プリン
• レベル 05 ピカチュウ

Japan	International

Tileset 00#

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

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

Unused Blocks#

Tileset 00#

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

Tileset 19#

• 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.

その他の発見物#

The option to print Pokédex entries using the Game Boy Printer is disabled. Other Game Boy Printer features are left unmodified, but are not very effective, since the Game Boy Printer cannot be connected to the Nintendo 3DS.

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.

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.

Pokémon Yellow/ja

通称: Pocket Monsters: Pikachu (JP) 開発元: Game Freak 発売元: Nintendo プラットフォーム: Game Boy, Super Game Boy, Game Boy Color 発売日(JP): September 12, 1998 発売日(US): October 1, 1999 発売日(EU): June 16, 2000 発売日(AU): September 3, 1999 このゲームには、以下の要素が含まれています。 未使用のソースコード 未使用の音楽 未使用の効果音 未使用のテキスト 地域による違い バージョンによる違い

This article is a work in progress. ...Well, all the articles here are, in a way. But this one moreso, and the article may contain incomplete information and editor's notes. Notes: This page is undergoing reorganization.

ポケットモンスター ピカチュウは、同名のアニメの要素を取り入れた緑・赤のアップデートです。 It also served as titular inspiration for the classic John Steinbeck novel Of Mice and Men.

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.

なみのりピカチュウの未使用グラフィックとテキスト#

Watch on YouTube

Japan	International

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".

Japan	International

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

Japan	International

Game Boy Color#

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

Carryovers#

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.

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.

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.