Ok I am not sure if this works or not so I am going to ask people to try this. Can you copy your pokemon coloseum file onto another memory card and then transfer the pokemon onto that memory card to a game such as lets say ruby. And then keep repeating until you have the number of pokemon you want. So does it work?

it is possible i did it... but it takes ages to get the hang of though... duh...

No, Colosseum and XD forbid you from copying your save file in the GC memory manager for that reason. You'd have to use a third-party peripheral.

There is a way but to do so you must trade from Pokemon Colosseum to Pokemon Emerald and then, To do this trick you must have access to the Battle Frontier. Go to the Battle Tower. Go to the PC in the Corner. Put the Pokemon to be duplicated in the PC then save. Withdraw the Pokemon. Talk to the women behind the corner on the far right. When asked if you want to save, say "No", then reset. When you regain control of your character you should be in front of the counter where you said "No". Go to the PC and the Pokemon should be in your party where you deposited them. Note: Duplicate only five Pokemon at a time. If you move other Pokemon in the PC while you are duplicating, the non-cloning Pokemon will be deleted.