Things You'll Need
Instructions
Insert ̶0;Pokemon: HeartGold̶1; into the smaller slot on the Nintendo DS. Insert the Action Replay cartridge into the larger slot intended for Game Boy Advance games. Insert any Game Boy Advance game into the slot on the Action Replay cartridge. It does not matter what game is inserted into the Action Replay, but this slot must be filled for it to function properly.
Turn on the system. The menu screen appears after a few seconds. Press the ̶0;MAX DRIVE DS̶1; button on the screen.
Press the user name the Action Replay save file is stored under.
Press the ̶0;RESTORE CART̶1; button in the menu. A list of all the saved games on your Action Replay cartridge appears.
Press the save file you want to use. Press the ̶0;DONE̶1; button to move this save file on the cartridge. The save data on the ̶0;Pokemon: HeartGold̶1; cartridge is completely rewritten by the Action Replay save. There is no way to recover the overwritten save at this point.
Turn off the Nintendo DS. Remove the Action Replay cartridge. The Action Replay save is the one loaded when you start ̶0;Pokemon: HeartGold̶1; again.