Things You'll Need
Instructions
Connect the GameShark. It goes into your Game Boy Advance̵7;s cartridge slot. Insert the ̶0;Pokémon FireRed Version̶1; cartridge into the GameShark and power on the system.
Select ̶0;Code Entry̶1; and enter the master code to make all subsequent codes work: 9820F6 AE8203 51F0D8 DF70D1 407403 064659.
Enter the shiny Pokémon cheat: 5DDF4406391D 838EED7C52C0 718812FE9DED 68755A0BCC17 88BBC0A65C0F A903F2EB8D85 EA0446C4E6E3.
Enter the code for Celebi: 4AEC27E8 A5FF1540.
Start playing the game and head to a grassy area. The first Pokémon you encounter will be a shiny (red) Celebi. Capture it. Note that unless you turn off the shiny Pokémon cheat, all Pokémon you encounter will be in their shiny forms.