From Glitch City Laboratories
|This article is a summary page for variations of certain glitches or phenomena such as Pokémon Cloning, glitch myths, beta elements, or a collective term for variations of glitch Pokémon which share similar names, sprites or other information.
A glitch Pokémon
with an invalid checksum after being labelled as a "Bad EGG" on Pokémon Ruby and Sapphire.
A glitch Pokémon
with a hexadecimal identifier of 1EF (495) using the error handler "Bad Egg" as its name, encountered in battle within Pokémon Diamond and Pearl.
The term "Bad EGG" in the Generation III Pokémon games and later "Bad Egg" in the Generation IV games, refers to an error handler which was presumably, originally used by the game developers to refer to individual Pokémon (as eggs) with stats which do not conform to the original algorithms suggesting what stats that Pokémon should have, such as the individual values, base stats and ability of that Pokémon. For example, of an egg which was illegitimately (without writing to the checksum) given an excessively large attack stat for when it should hatch. Normally, when a player recieves an egg, the game should write to the checksum by using an algorithm to calculate the total of unencrypted Pokémon data. If the game later considers the checksum to be invalid, (i.e. if it is greater or lower than a possible value based on XOR calculations - perhaps if the EV total is greater than 510) the game will interpret the Egg as a "Bad Egg".
However, since after Generation II Pokémon in one sense are simply eggs with an additional byte with a value of 01 (ON) it is possible that a hatched Pokémon would also be taken by the game as a 'Bad Egg', which could suggest that the game developers did not expect other game developers to accidentally invalidate the checksum of a gift Pokémon with variable characteristics for example.
Like ordinary eggs, Bad Eggs under normal circumstances can never be released and when the player attempts to view one's summary screen the game will not give the details of the Pokémon (if it was not an egg) but rather, the game would display another interface which suggests how long it would be until the egg hatches.
In non handheld Pokémon games
A Bad Egg being defeated by a Chimchar
in Pokémon Battle Revolution. Note the distinctive brown spots instead of the usual green.
It is notable that the error handler "Bad EGG", or "Bad Egg" is still used in Pokémon Colosseum, Pokémon XD and Pokémon Battle Revolution; despite the fact that eggs alone are normally unobtainable within these games. For this reason, it could be suggested that it is used simply so that the game does not crash. Furthermore, Eggs and Bad Eggs even use their own unique models and strangely appear as eggs with brown spots instead of the usual green. In Pokémon Battle Revolution, unless the player turns the narration off the game will crash when a Bad Egg is sent into battle as such data is undefined.
If a Pokémon with an EV total greater than 510 is uploaded on to Pokémon Battle Revolution, the game will recheck the checksum and render that Pokémon as a Bad Egg.
In Generation IV
As a Pokémon species
Main article: GlitchDex/DP:495
Unlike in the third generation of Pokémon games, as well as appearing when a Pokémon's checksum is found to be invalid, for unknown reasons Bad Eggs actually have their own defined identifier of 495 (1EF) in the species byte. Such a 'Pokémon' if encountered in the wild by the use of a game-altering device will have Splash as its only move but it has no defined data for its cry, hence it uses the cry of a Bulbasaur (the first valid Pokémon in the species byte).
Rumours of Nintendo using Bad Eggs to punish cheaters
Main article: Glitch Myths
It is notable that error handlers such as "Bad Egg" are sometimes misinterpretated as punishments from Nintendo for when players illegitimately (through the use of a game-altering device) change the stats of Pokémon. Whilst Nintendo have not responded on such matters and such claims have not fully been proved to be false, it would be more likely (considering quality assurance) that these messages were simply used as error handlers when the original Pokémon Ruby and Sapphire were in development.