The date change exploit is an exploit in the Pokémon series, where the player can re-access certain daily events by manually changing the day of the week, either from in-game (Pokémon Gold, Silver and Crystal) or through the Nintendo DS or 3DS firmware (Generation IV, Generation VI).
Similar exploits include the Daylight Saving Time exploit and the midnight exploit. The latter can be used to change events in Pokémon games from Generation IV to Generation V that won't change with the date change exploit.
The menu that lets the player change the day of the week and time in Pokémon Gold and Silver
In Pokémon Gold and Silver and Pokémon Crystal, the day of the week can be changed by accessing the "The clock's time may be wrong" screen.
This screen can be accessed with the clock reset function with a suitable password.
In Pokémon Gold and Silver, the clock reset function can be accessed from the title screen with down, select and B and the password depends on the player's name, ID number and current money (see here for a password generator)
In Pokémon Crystal, the way to access the clock reset function was made more complicated. It can be accessed with this method:
- Hold down+select+B
- Release down+B, leaving select still pressed
- Hold left+up
- Let go of select
The password generation process in Pokémon Crystal may not have been changed.
(Thanks to the Pokémon Crystal disassembly)
On emulators that don't properly support the real-time clock, the 'The clock's time may be wrong' menu may appear without the password. Glitch Unown including the hex:83 and hex:84 types in Pokémon Gold and Silver are capable of getting the menu to appear as well after a Glitch Dimension.
Things that the player can do after changing the day of the week include but are likely not limited to: accessing the Bug-Catching Contest from any day of the week rather than a Tuesday, Thursday or Saturday, and causing the move tutor outside of the Goldenrod Game Corner in Pokémon Crystal to appear.
The date change exploit can be used to do a limited number of things such as:
All the player needs to do is change the day of the week on their Nintendo DS or Nintendo 3DS firmware, though the midnight exploit has to be used if the player wants to cheat for most other events, such as changing swarm Pokémon.