Mario vs Luigi Agni Kai

One sibling (with the ability to shoot fire from his fists) is inferior to his other sibling (who is better all around, but a bit slippery and unpredictable, and who can also shoot different colored flames from their hand, and lightning) but is more of a main character. Now it's time for the ultimate showdown as these two siblings duel in the showdown that was always meant to be.

(In short, Mario is Zuko because he can shoot fire, and Luigi is Azula because they are siblings, Luigi is younger (yet arguably better because he can jump higher), he can shoot different colored fire (azula can shoot blue, he shoots green) and he can shoot lightning, and he's a little bit crazier than mario is.)