Did anyone else notice that Bowser + Carrie = God mode? Seriously, Bowser's only real limiting factors are his sluggishness and the fact that he can only breathe fire on the ground, but when you use Carrie, he becomes much faster and he can then breathe fire while jumping and just becomes an unstoppable force of destruction. The second time I fought Mimi looked like it might be difficult, but I have no idea because as soon as the chance presented itself, I leapt in the air and baked the bitch and her projectiles before she even had a chance to attack.
Also, for those who don't know, Bowser's dialogue is, by far, some of the best I've seen in a videogame, ever. Tippi says, "Looks like they went into that pipe." and Bowser replies, "What am I, blind? Shut UP." Too perfect...