Kyoshi: Kyoshi vs. Ozai would be a very short fight. She's taking down Ozai's blimp with a giant pillar, and then squashing Ozai like a bug. There is basically no fight.
Yangchen: Similar to Kyoshi vs. Ozai, this fight would be quick. She'd probably start off like Aang. Just when Ozai lands to start talking about providence, she rips the air out of him and suffocates him.
Korra: This wouldn't be as easy as the last two, but I think Korra's got this. Instead of waiting for Ozai to jump off his pedestal, Korra is going into the Avatar State, charging him, and pushing him off. Unlike Aang, she isn't going to run away at first. This leaves Ozai in a bad position. Ozai is a coward. When he sees something more powerful then him, he runs. Ozai's unlikely to use lightning on the run. He's just going to fly and hope that Korra doesn't grab him. If he were to fight back, Korra's just going to slam him. Eventually, she'd trap Ozai and either a) kill him, or b) take his bending. Anyway, Korra wins.
Kuruk: Kuruk is blessed with two powers. One of them is to be able to punch like Superman (he hit Father Glowworm so hard he nearly created a hole in the spirit world), and the other is getting back up no matter what. Kuruk's fight with Ozai is probably going to be slow, but by the end of it, Ozai is going to be black and blue. And also dead.
Roku: Roku is going to come in there calm. He's then going to go nuts, but right before he kills Ozai, he traps Ozai and waits out the comet. Then he scolds Ozai for trying to take over the world, gets on his dragon, and waits for the next volcano to fight. In all seriousness, I think Roku could win against Ozai. I just don't feel the aftermath would be good.
Wan: This would be the shortest fight. Wan's bending is out of date. He only knows how to actually firebend correctly (aka dragon style), and his only special ability is creating a magic cloud that carries him around (which I still want to know what happened to that technique). Ozai has the advantage. Wan would fall to Ozai's lightning and fire.
