Things You'll Need
Instructions
Purchase Pokemon Colosseum with the bonus disk. Jirachi was a reward to Pokemon players who preordered Pokemon Colosseum. The only way to "catch" Jirachi is through using that bonus disk in your Nintendo Game Cube. Used copies can sometimes be found in game stores such as Gamestop, Game Crazy and EB Games.
The bonus disk will have a "preview" of the Pokemon movie "Jirachi Wish Maker." Finish the preview, then proceed to Step 3.
Run Pokemon Ruby. Place your Pokemon Ruby game cartridge into your Game Boy Advance and start the game.
Link your Game Boy to the Game Cube. Using the link cable (they retail for about $4), connect your Game Boy running Pokemon Ruby to your Game Cube running Pokemon Colosseum. You will now have Jirachi on Pokemon Ruby.