So you are aware, this does not actually save you time. Pokemon in the breeders stop breeding and will never produce an egg while you are in another region than where that particular breeder is at. So, while you are in Hoenn any pokemon in the Kanto breeder will stop working to produce an egg and vice versa.
I don't see him on the list you made so we can assume this means that smackdown will get Shelton Benjamin? I don't know why I am treating him as something special I mean he wasn't bad but I don't remember anywhere where he stuck like other people have.
Its probably just something that happens as he uses up his energy, Have we ever seen buu in a prolonged fight? Don't think so. But we know he had been training for quite some time at that point and was quite exhausted/out of energy when it was all said and done.