Candidate: Pyro.

Intro: Pyro has his back to the screen, staring at a wall of fire. He turns towards the opponent and readies his flamethrower.

Costume 1: Pyro in his default appearance and flamethrower.

Costume 2: Pyro with the back burner flamethrower, and fireman helmet from bioshock infinite (it was an actual promotion. Look it up), along with the mercenary badge.

Victory pose: Pyro raises his flamethrower in the air and laughs, muffled. He then starts blasting flames all around him.

Babality: Pyro looks around in confusion, then uses nearby sticks to light a campfire.

Fatalities:

(Pyromaniac) Pyro gets out his axe and hacks the opponent's legs off, then arms. While they writhe in agony, as nothing but a limbless stump, Pyro stabs the end of his flamethrower into the opponent's stomach then fires (get it?), incinerating their insides.

(Caution: flammable) Pyro blasts his flamethrower at the opponent, igniting them. As they scream in horror as their flesh sizzles, Pyro gets out a flare gun and jams it into the opponent's mouth. He fires, and watches as the opponent's head lights up red, then bursts into flames. They fall, and Pyro exclaims a muffled phrase.