From Glitch City Laboratories
The Change Player Color glitch is one which allows the player to change colors of his or her character on Pokémon G/S/C.
- Start a game as either a boy or a girl and save it.
- Start a new game as the opposite gender as the first save.
- Save the game, but turn off the game while it says "SAVING...DO NOT TURN OFF THE POWER".
- When the player restarts, his or her character should be the wrong color.
- The player can try this glitch without starting a New Game by skipping the first step, but he or she will lose all of the Pokémon that he or she has saved on the PC.
- Performing this glitch will unlock Mystery Gift.