Things You'll Need
Instructions
Insert the Action Replay DSi cartridge into your Nintendo DS and turn on the Nintendo DS.
Scroll through the listings of available codes and press "A" to select the codes you want. The Nintendo DSi will automatically recognize your "Pokemon Diamond" or "Pokemon Pearl" game and provide a listing of pre-programmed codes.
Turn off your DS when finished selecting codes and replace the Action Replay DSi cartridge with your game.
Turn on the DS and start the game. All of the selected cheats will automatically take effect once you begin playing.