But he has a weakness: happiness. Make him happy and he'll be vulnerable. Maybe he likes candy. Give him some candy, jolly candy man!
or maybe when he's the hulk you could just rub his belly, then when he stats to turn to bruce you shoot him... with a candy gun
haha... a candy gun!! haha
Then sit back, relax, and smoke a candy cigarette. Basking in your glory for destroying the huge green behemoth with your bubble gum bullets.