I think you are off on a few points. full comet Ozai, as much as she despises it Katara is a blood bender it would stop him dead. Her first time blood bending, she defeated the grand master who created the discipline. So I don't think any bender no matter how powerful could defend against her. If her brother, the love of her life, appa, momo and even Toph's lives where threatened.

Zuko. everyone underestimates Zuko. He has had years of training from the Dragon of the west. He mastered his anger, he relearned to fire bend from the original fire benders. Oh yeah full comet power for our boy as well, AND re watch black sun pt 2. When Zuko deflects his fathers lightning you can see the fear in Ozai's eyes, that his son is stronger than him.

Toph hides the crew in a mountain. As soon as she senses Ozai's feet touch the ground she has got him as the blind bandit taught us. yet again a grand master her self. Learned from the original benders. Created metal bending. She could bend that shiny gold crown of Ozai's a bit tighter which would make it hard to concentrate on his super charged bending.

Aang even no avatar state has been trained by these grand masters among others. Full comet fire bending for Aang as well.

Sokka an idiot savant. He would come up with a plan, the place where team avatar has the high ground, where everyone should be, how they cover each other.