Bowser Bomb is the Down Special Move move of Bowser. If Bowser is in midair when using this move, he slams to the ground with a butt-stomp. If he's on the ground doing this, he will leap forward diagonally before performing the butt-stomp. In Super Smash Bros. Brawl, Bowser gains some hyper armor at the start-up of the move.
This special attack is shared by Giga Bowser, both in his boss appearance in Super Smash Bros. Melee and in his playable appearance in Brawl.
Yoshi has a similar move, the Yoshi Bomb though it produces disruptive stars upon landing.
The move is based on Bowser's attack pattern in Super Mario Bros. 3