If you have the Colosseum pre-order bonus disc, you can put one Jirachi on your Ruby/Sapphire games. You can trade an unlimited amount of Jirachi from the bonus disc, but only one Jirachi can be put on each Ruby/Sapphire game. If you restart your R/S game, you can get another Jirachi on it. As long as you have the Pokédex, your starter Pokémon, and have saved your game in a Pokémon Center, you will be able to get a Jirachi on your game. So, if you really want a ton of Jirachi, you can keep restarting a Ruby/Sapphire game and putting a Jirachi on it, and then trade it to another game, and keep doing that if that is what you want. ^_^