Things You'll Need
Instructions
Hook the Action Replay to the Game Boy Advance via the game cartridge slot, and then slide the "Pokemon FireRed Version" cartridge into the Action Replay.
Start the system and go to the code entry screen.
Enter the master code for the US version of "Pokémon FireRed Version," which is as follows: 72BC6DFB E9CA5465 A47FB2DC 1AF3CA86.
Enter the Jirachi Pokémon encounter code, which is as follows: 17543C48 E65E0B97 FFF032FD FAF9AFD2.
Start playing the game and you will encounter Jirachi in the wild during your first Pokémon encounter. Battle and capture Jirachi as you would any wild Pokémon.