List of glitches in Generation I

Pokémon Red, Green, Blue, and Yellow

This section is incomplete. Please feel free to edit this section to add missing information and complete it. Reason: cf. English and other localizations with the original Japanese releases

NOTE: The following glitches affect all Game Boy versions of Pokémon Red and Green (1.0 and 1.1) and of Japanese Pokémon Yellow (1.0 to 1.3) unless noted otherwise.

Experience PC withdrawing glitch

In Generation I, attempting to withdraw a level 1 Pokémon using the "Medium Slow" growth algorithm will softlock the game. This also applies to Pokémon using the "Medium Fast" growth algorithm for Level 255, "Fast" for Level 255, and "Slow" for Level 237.

Certain glitch Pokémon use invalid growth algorithms and have the game freeze when they are withdrawn at specific levels as well. For example, in Pokémon Red and Blue, 'M (00) uses an invalid experience curve 26 and the game will freeze if the player attempts to withdraw a level 0 'M (00). Level 0 'M can be found with the old man glitch if the player does not pick a preset name.

Additionally, if a Pokémon in the "Medium-Slow" growth algorithm is withdrawn between Levels 245 to 255, it will become a Pokémon with a level between 59 and 125, depending on the exact Level of the Pokémon deposited. A Pokémon in the "Slow" growth algorithm that is withdrawn between 238 and 255 will become a Pokémon with a level between 39 and 146. A Pokémon withdrawn in this manner will have its stats recalculated, which may lead to it having more HP than its maximum HP.^[1][2]

Hall of Fame corruption

Some corrupted Hall of Fame entries

Main article: MissingNo.#Glitches caused

When glitch Pokémon have been seen on the save file, the player's Hall of Fame is badly corrupted with entirely different Pokémon, even glitch Pokémon, and very glitched characters, names and levels. This does not affect the Pokémon themselves, rather the data seen in the Hall of Fame, and is caused by the contents of the sprite decompression buffer that is stored in SRAM overflowing into memory allocated for save data when a glitch Pokémon's sprite is decompressed.

Item duplication glitch

Main article: Item duplication glitch

Item underflow glitch

Main article: Item underflow

Leveling past 100

In Generation I and II, if a Pokémon is obtained at a level above 100, it can be leveled up with Rare Candies up to level 255. If a Rare Candy is used on a level 255 Pokémon, its level will be reset to 0 due to an overflow in a single byte. If a Pokémon above level 100 levels up due to experience, its level will be reset to 100.

In Generation II, if a Pokémon levels "down" to 100 in battle, it will attempt to learn all of its level-up moves between levels 1 and 100 (other than moves it already knows).

Pokémon merging

Main article: Pokémon merge glitch

Pokémon Storage System cloning

Main article: Cloning glitches#Storage system method

Pokémon Storage System healthy party deposit

It is possible for the player to deposit all Pokémon except fainted ones and a black out will occur but only after four steps in the same session. In Red and Blue it is possible to progress further by saving the game before traveling four steps to reset the 'remaining step count' to 4 when the game is reset, though this is no longer the case in Pokémon Yellow because the remaining step count was changed to default to 1 step. The player immediately has a black out if entering a battle with just fainted Pokémon.

Rhydon glitch

Main article: Rhydon glitch

Save corruption

In Red, Blue, and Yellow, with no save file, when the player saves the game and turns off the power a little time after the Yes/No box disappears the player will have 255 Pokémon in the party the next time the file is loaded.

If the player turns the power off at the wrong time, the save file will either be corrupted or will appear normal. The right time to pull off the glitch is about twenty frames after the A button is pressed, but in Yellow it is about ten frames later.

The first few Pokémon are level 255 'M (FF) (Red/Blue) or Q ◣ (Yellow), with all of their stats as "F35" (65535), four TM55 as their moves with 63/0 PP and with a nickname and OT of many repeating "9"s. Pokémon past number six do not have all of these properties.

The data regarding Pokémon past the sixth position use other parts of the game's memory misinterpreted as Pokémon data, therefore swapping these Pokémon around or healing them can affect the game. If the player switches the first Pokémon with the tenth Pokémon, they will have 255 items. Switching the items past slot 20 will allow for more precise memory editing because there are only two pairs of memory addresses manipulated; displayed as an item and item quantity, while a "post-six" Pokémon uses many more bytes.

After performing the glitch, the poison effect will occur as the player walks around. In English versions, swapping the first-ninth Pokémon with the tenth will cause to player to have seen and owned 152 Pokémon in the Pokédex.

The Pokémon in the 10th slot will change to a different glitch Pokémon as the player walks around to different areas, making it theroetically possible to obtain every Glitch Pokémon in the game.

Using the following equation, it is possible to calculate what memory address any item, including invalid items is using, provided that the memory address is odd.

Memory address = [First item position address -1] + [Cursor position] + ([Cursor position -1])^[3]

The item address that follows an item is displayed as a quantity.

Beating the game quickly

As there are no memory protection measures in place in the Generation I and Generation II games, it is possible to use this glitch to do a number of things, such as beating the game in under five minutes. Below is one method of doing this that requires no luck manipulation:

In Pokémon Yellow, the memory address D364 is used for the last map location for walking through certain exits, including the exit for Red's house and the first item position address is D31D. This means that the correct cursor position can be expressed as:

D364 = D31C + [cursor position] + [cursor position -1]

This has no actual answer because D364 (54116) is even, so the address must be a quantity, but if D363 is used, the answer comes to hex: 24 (dec: 36). Therefore, the memory address D363 (current block of the player's X-position) corresponds to item position 36 (hex: 24) and the quantity of item 36 is the aforementioned warp location address. The cursor position in hexadecimal can be checked by highlighting an item in game and checking the memory address CC35.

As the index number of Pallet Town is 0, the player can access 255 locations by tossing the 36th item (as tossing one ×0 item causes an underflow to 255). The index number of the Hall of Fame room is 118, so the player must toss exactly 138 of item 36 to change the warp destination to the Hall of Fame. If the player stands on the right side of the exit mat item 36 should be a Master Ball, while if the player stands on the left side of the exit mat, it should be the hex:00 glitch item which would appear as some glitchy blocks with a multiplication sign in it.

In Japanese versions

The glitch works in Japanese Blue but the game has to be reset some time after the "!" mark appears in "(PLAYERNAME)はレポートに しっかり かきのこした!". In Japanese Yellow it is possible with the same procedure as English Red/Blue and Yellow, but in order to corrupt the number of items the player has to replace the ninth Pokémon instead of the tenth to avoid a freeze after closing the items pack.

Save data carryover

Using a procedure similar to the save corruption glitch, it's possible to begin a new save file, but having the party Pokémon from the previous save file. With an already existing save file, player must start a new game then save to overwrite the previous save, but turn off the game or reset shortly after the Yes/No box disappears. The exact timing is a difficult two frame window, doing it too early corrupts the previous save file and doing it too late completely overwrites the previous save file.

If successful, the player will begin the new save data while having the party Pokémon from the previous save file in their party. This glitch can be used at the beginning of the game to obtain all three first partner Pokémon without trading.

Trade cloning

Main article: Cloning glitches#Trading method

Pokémon Red, Green, and Blue (Japanese)

NOTE: The following glitches affect all Game Boy versions of Pokémon Red and Green (1.0 and 1.1) unless noted otherwise.

Empty Pokémon List

If the player withdraws the Potion from the PC at the very start of their adventure (meaning before they receive their first partner Pokémon) and then attempts using it, an empty Pokémon List will appear and the Potion can be used, albeit to no effect. This was fixed for international releases and Pokémon Yellow, which will state "You don't have any^RB/a^Y POKéMON!" (Japanese: ポケモンが　1ぴきも　いない！).

Full Box glitch

If the player has six Pokémon in their party and their current Pokémon Storage System Box is full before watching the old man's catching demonstration, the game will state that the box is full when the old man tries to capture the Weedle. The game will try to use the Poké Ball again infinitely afterwards, and every attempt results in this message causing an infinite loop. This forces the player to either reset the game or turn the power off. This is because the game thinks that the player is catching a Pokémon, even though it's actually the old man, the game produces a "temporary" Pokémon to hold, and if the catching demonstration ends, that caught Pokémon is deleted.

This glitch was fixed in the Japanese version of Pokémon Yellow and in the localizations.

Select glitches

Main article: Select glitches

Dokokashira door glitch

Main article: Dokokashira door glitch

Second type glitch

Main article: Second type glitch

Pokémon Yellow

NOTE: The following glitches affect all Game Boy versions of Japanese Pokémon Yellow (1.0 to 1.3) unless noted otherwise.

Friendship item effect

This causes a no-effect item to still increase Pikachu's friendship value. For example, attempting to use a Potion on a Pikachu that has fainted or has full health, an Antidote when Pikachu is not poisoned, Calcium when Pikachu has already has at least 25600 Special stat experience, or X Special when the Special stat has already been raised 6 stages in battle. This does not consume the item, so the same item can repeatedly increase Pikachu's friendship.

This glitch was fixed in Generation II.

Time Capsule glitches

These glitches involve communication with Generation II games.

Time Capsule exploit

Main article: Time Capsule exploit

Trade evolution learnset oversight

Generation I Pokémon that can evolve by trading can be taught glitch moves through this glitch. This can be achieved by trading a trade evolution Pokémon from a Generation I game to a Generation II, at a level where its evolved form will learn a move not in Generation I. Trading the Pokémon back to the Generation I game will cause that move to become a glitch move.

For example, trading a level 34 Graveler from Pokémon Red to Pokémon Gold will make the Graveler evolve into Golem. Since it is level 34, it will learn Rollout. If it is then traded back to Pokémon Red, it will still have the move, but the game won't recognize it properly since it is a Generation II move, so it will become TM05.

Poké Transporter and Pokémon Bank glitches

Pokémon Bank hex:FF glitch Pokémon glitch

	This glitch is in need of research. Reason: Test other glitch Pokémon. Check if there are other ways to prepare the box. You can discuss this on the talk page.

If a player attempts to transfer a Box 1 that has one Pokémon, an 'M (00) or 3TrainerPoké $ and eighteen Pokémon (in that order) through Poké Transporter and a 3DS Virtual Console versions of Red, Blue and Yellow, the Generation I game will be left with one 'M (FF) or Q ◣ which is an unstable hybrid Pokémon of 'M (00) or 3TrainerPoké $ with a blank OT, ID of 00000 and no moves.

This Pokémon can be used for the Pokémon merge glitch unless stabilized through Day Care back into 'M (00) or 3TrainerPoké $.

These are audio quirks that generally do not affect gameplay.

Pokémon Red, Green, and Blue

New-game Nidorino cry oversight

During the new game tutorial, the game shows Nidorino's sprite but plays Nidorina's cry.

These are graphical quirks that generally do not affect gameplay.

Pokémon Red, Green, Blue, and Yellow

Menu glitch

If the player holds A when the game is saving, the menu won't disappear until player stops holding A.

Red's transparent white pixels

Pidgeotto behind Red, with Red's white pixels treated as transparent

Slow motion animation of Magikarp moving behing Red

In Pokémon Red and Blue's title screen, Red's white pixels are treated as transparent.

This glitch is visible once a Pokémon quickly moves to the left and passes behind Red. At this point, the Pokémon will be visible through Red's white pixels. This includes the white portions of his hat, sleeves, eyes, face, pants, shoes, and gloves.

Town Map selection oversight

In this generation, if a player currently on Route 1 opens the Town Map, pressing up at first will apparently do nothing, as the selection will go from Route 1 (the current place) to Route 1 again. This is based on the fact that no matter where the player is, pressing up will initially move the cursor to Route 1. Therefore, the player will need to press up twice to select the next place, which is Viridian City.

Similarly, if the player is currently in the Power Plant, pressing down at first will apparently do nothing; they will need to press down twice to select the previous place, which is Indigo Plateau.

Trade menu palette glitch

If the player sees the data of any Pokémon, the trade menu palette will change its colors depending on the color of the Pokémon and the HP it has at the moment. This bug was fixed in Pokémon Yellow.

Pokémon Red and Blue (English)

Instant Text trick

If the player goes into the Cerulean City Bike Shop without a bike voucher and cancels out exiting the shopping menu of the bike shop, the game never resets a text based flag. Instead of the game showing all the text character by character, it will instead now show all text on screen instantly. Going back to the shop later and buying the bike will reset the flag.

Pokémon Blue

Purple Jigglypuff oversight

In both the Japanese and English versions of Pokémon Blue, Jigglypuff appears purple instead of pink when battling Gengar in the game intro if this game is played in color.

In Pokémon battles and the summary screen, Jigglypuff uses the pink Pokémon palette while Gengar uses the purple Pokémon palette. However, they both share the purple palette in this game intro cutscene.

This is a leftover from the earlier Japanese games Pokémon Red and Green, when two purple Pokémon battled instead: Gengar vs. Nidorino (which is also seen in the international versions of Pokémon Red).