Bugs Bunny would win. Bugs Bunny is probably capable of doing more horrifying things to the other 2 then can be thought possible. it would not be simply tricks. There will be anvils involved.
lets start with bugs vs Disney in general. Disney characters are normally sane. there maybe magic in volved, but rarely do they have have a hole or a tunnel that can be slapped on a wall. When you look at Acme's extensive inventory of things, mickey has no chance. He isn't capable of try violence or bug's kind of comedy. He also isn't based on Oscar Shapely like Bugs is, so he automatically looses. (super points to anyone who knows who is and where Oscar Shapely is from.)
Then we have mario. Mario to me is just totally random, and i'm not sure he applies to this, lets do it anyway. Jump man here would again, jump until a hole in the floor. that portable tunnel/ hole alone can destroy them all.
I mean seriously, what were you people thinking? looney tunes is far more efficient at destruction than either of those other 2 jokes.