Going with Aang on this one. The bloodlust stipulation will lead to him instantly going into the Avatar State as soon as the battle begins, already giving him a huge edge over the team. Plus, he has the speed to dodge anything they throw at him (via avoiding Ozai's lightning bolts) and can oneshot most of them if they get close.

The only real threats to him are Electro and Sand-Man but Marko's fight with Black-Suit Spider-Man showed that he can be damaged if hit hard enough (plus it doesn't do him any favors that his other weakness is water) and I'm sure he can take down Electro with enough blunt force.