These glitches occur in Pokémon Gold and Silver (and REDIRECT Template:Crystal with arbitrary code execution) when data for the player's mailbox becomes corrupted with glitch mail. When the player has an excessive number of mail, viewing the mailbox may cause a Glitch City.
The glitches are often accompanied by Trainer House glitches, a delivery man appearing in Pokémon Centers and/or the Mystery Gift option becoming available on the menu without having to talk to the girl in green on Goldenrod City Department Store's fifth floor.
The glitch can be activated by viewing certain glitch Unown in the Pokédex, which are available through ????? party overloading or arbitrary code execution (e.g. via the Coin Case glitch).
Glitch mail refers to glitchy mail sometimes generated inside the player's mail box in Generation II after corruption.
Glitch mail may be of an invalid type (meaning that it has an index number which is not used for a valid mail item such as Flower Mail), and may display glitch text, either in the contents or message itself, or both. Glitch mail may be signed from 'GREEN', which is from the control character hex:39, and will appear in "00 39" corruption patterns.
A glitch mail will become an item when it is put into the bag, depending on the mail item's index number. As mentioned above, a mail item in the mailbox may not be of a valid kind (this is the case with most index numbers), so it is possible to obtain items such as "?" (hex:00), which will not bring up a screen to attach a message to it when the item is held by a Pokémon.
Excessive mail glitchWhen there is an excessive amount of mail (the maximum is meant to be 10), glitches will occur when the mail box is opened.
Effects in Pokémon Gold and Silver include:
Corruption of the overworld. A changed walking animation. Corruption of the start menu options. A corrupted wild Pokémon, and a forced 'link battle'.
Obtaining glitch mail
More research is needed for this article.
Reason given: Document more effects of it. Can a Glitch Pokémon evolve if its sprite and name are "stable" enough? Are there many glitch cries available for Glitch Pokémon? List Glitch Type Sprites that could cause interesting effects. Study the causes and effects of the corruption of the PC Pokémon Selection in Fr/Lg. Test again the effect of Pokédex entries of Glitch Pokémon.
This effect is not too uncommon and can occur after cheating, but there is a way to get it without cheating.
Glitch mail in the player's box, and others effects such as a glitch Trainer House Trainer can be obtained with the Unown SRAM corruption glitch, which can be pulled off by viewing a certain glitch Unown in Unown Mode of the Pokédex.
Glitch Unown can be obtained with the ????? party overloading, and a working value that creates glitch mail is the hex:24 (5th Pokémon's Defense is 36 modulo 256) type.
Invalid glitch mail typesMany and possibly all but one invalid glitch mail types look like the Flower Mail but with the wrong colors. The color changes are different between Pokémon Gold/Silver and Pokémon Crystal.
|Type||Background color||Five-petal flower and border color||Four-petal flower and name field color||Oddish color|
|Flower Mail||Light green||Orange||Red||Red|
|General glitch mail type (Gold/Silver)||Purple||Green||White||Black|
|General glitch mail type (Crystal)||Light blue||Blue||Pink||Red|
In Pokémon Gold and Silver, the hex:FF invalid glitch mail type simply loads a purple screen, but the game does not freeze and the player can return to the mail box.
In Pokémon Crystal, the hex:FF invalid glitch mail type causes a completely different effect. It forces an unexpected reset (but not a Glitch Dimension) and many values are corrupted from CFBB-E0A4 (corruption of values to hex:07 has only been reported as of yet). Many of these values are unchanged when the player selects 'continue' and bad effects on the game are noticeable from there, but no apparent corruption effects are noticeable when the player selects 'new game'
See this thread for more information.