I have a question for xd and coluseum can you transfer pokemon from your gba back and fourth just like the stadiums?

I'm assuming you mean being able to use pokemon from your Game Boy games in Colosseum battles. First you need a GCN/GBA link cord. You can get one at any game store for, like, 10 or 15 dollars. Then you hook up your Game Boy with the game that contains the Pokemon you want to use in Colosseum/XD. Now just go to the "Battle Now" menu (I only have Colosseum, so I'm not sure if this looks different in XD), and select "Register." Then select that you want to register GBA pokemon, rather than Story Mode ones. Here there is a screen that tells you to connect the GBA to the GCN and turn on the Game Boy. After a few moments your pokemon will appear on the screen, and it will say "Do you want to use this team?" Select yes. Now your Pokemon are registered on Colosseum/XD. When you want to do a battle, select that you want to use GBA pokemon and it will ask if you want to use your Registered GBA team.

And if you want to use them in Story Mode you have to first beat the game then go to the Trading Center where you once again must hook up the Game Boy to the Gamecube, and now you can trade your Story Mode pokemon with your Game Boy ones.