Well, I can't really help much there, but I'm pretty sure the Pokémon XD main character/hero is named Michael.. (Wish I could rename the character..) It should be it, because I thought I saw it somewhere.
And Colosseum, well.. I'm not entirely sure because I saw/read both names so I don't know 100%. One was Seth, and the other is Wes. Maybe one is Japanese or something? I don't know. Rui is the girl following you.. I'm pretty sure about that too.
Hope I helped a bit. Oh, and Jovi is Michael's sister's name, but that doesn't change. ^^
Correct me if I'm wrong though.