December 11, 2019, 02:57:46 am
Mystery Gift item corruption is one of the possible SRAM glitches in Generation II.
These glitches occur in Pokémon Gold and Silver (and Pokémon Crystal with arbitrary code execution) when a specific Mystery Gift item is enabled on the second floor of a Pokémon Center. This is due to the game writing a value to ABE2 in SRAM bank 0.
The glitches are often accompanied by 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, Mailbox glitches and Trainer House glitches.
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).