I have no clue what Bomberman's Final Smash would be. Maybe he could use that Green Jet Pack from Bomberman Hero and be able to fly around and bomb everyone. I don't know though. And to think, R.O.B. is given the spot instead of a cool character. The spot that could've been for Bomberman (though still unlikely he would get it) is isntead used by that stupid R.O.B.!!
Besides, considering how barely anyone knows about Bomberman, he most likely wouldn't have been in Brawl to begin with.