Alright, I decided to work on Boo for a while. Roy's giving me problems, even though I fixed the arms. He just won't work in-game, and a part of his leg is connected to his arm, which is not part of the rig. Iggy... he's just too tall. I'm not sure how to resize him.
As for Boo, he has good animations. I have two problems though. He doesn't show up well in CSS, being glitchy sometimes, like Petey. Also, when I try to play as him in-game, it reverts back to King Boo. I put Boo in the driver's model, and put it in the kart's Szs file, but it just keeps reverting back to the King.
On a side note, in CSS, his textures are good, unlike Roy and Iggy.