Things You'll Need
Instructions
Insert the GameShark into the Gameboy Advance cartridge.
Press the "Menu" option and press "Add codes." To open Ho-Oh, add the code "17543C48 E65E0B97 437065EF 67DF37EF." Save this and then resume playing Pokemon Fire Red. Go out on the grass, and the next wild Pokemon will be Ho-Oh. Weaken it and use a Pokeball to catch Ho-Oh.
To get Lugia, add the code "17543C48 E65E0B97 545C676A 51FFDC1C" into the GameShark. Resume the game, and the next wild Pokemon will be a Lugia. Weaken it and use a Pokeball to catch Lugia.
Trade with another Pokemon gamer. If the other person has Ho-Oh or Lugia in his party, you can negotiate with him and trade his Pokemon for one of your own. Use the Game Boy Advance link cable. Go to the Pokemon Center and go to the computer to commence a trade.