Fire Breath
Fire Breath is Bowser's standard special move. While holding the button, Bowser continuously exhales a stream of fire in front of him, which gradually decreases in length over time. In Brawl, the flames can also be angled up and down; and they will never completely recede, as they will in Melee, where Bowser will eventually begin to exhale smoke instead.
This special attack is shared by Giga Bowser, both in his boss appearance in Melee and in his playable appearance in Brawl. There is no time limit to how long the attack can be held in his Melee incarnation.
This move is also very similar to Charizard's Flamethrower.
Origin
Bowser's ability to breathe fire has been demonstrated in many game he's appeared in, including his debut in Super Mario Bros., where he would shoot fireballs at Mario.
