A full decade and this battle is still strongly argued as the show's magnum opus. That is something else. Figured I'd honor that by discussing some old pet peeves others tend to have about the battle, and why I think they actually work very well.
Ash should've won without Blaze:
I've seen (mostly old) posts here and there that claim that Ash relying on Blaze for the final fight is validating Paul. That if Ash needed Blaze so much that he'd purposely get Infernape Thundered to activate it, it means Paul was right all along. And honestly? It's true. Paul was getting validated. And the show is absolutely brilliant for it.
Ash spent most of the series avoiding Paul's beliefs as much as possible, especially with Chimchar. He outright refused to train Blaze simply because Paul did. And this overly narrow mindset bit him back hard when Blaze was inevitably activated, and Ash couldn't control it at all. They did need to master it. The key factor is how it was mastered, which was through Ash's compassion. Infernape was only able to master Blaze in time because its new master gave it the strength and positivity necessary to do so.
So yes, Ash does validate Paul by taking a massive risk with that Thunder. But he also validates himself, because it's only through his and Infernape's shared bond and willpower that the risk paid off. And he was still able to prove Infernape was strong on its own merits. They made it a point in all of its major victories to knock out opponents without Blaze.
Paul should've used his own Lake Acuity team:
This one's a lot more common nowadays, that Ash deserved to get his justice against the specific team that humiliated him back then. The thing is, Paul's LA team was a direct counterteam to Ash's. He had god knows how many strategies planned specifically to exploit Ash's Sinnoh Pokemon. Honestly, the whole battle was laregly meant to give a hard dose of Reality Ensues for Ash. He blindly tries to get vengeance without any sort of plan, and thinks his determination alone will carry him through. It doesn't.
So Ash finally admits he needs to change himself. He keeps training harder and better. He starts thinking things through more. And he even brings back his reserves to diversify, preventing Paul from making another hard counterteam. And even then, when he does bring back the Sinnoh team against Paul, it's directly addressed how much of a risk it is. But again, it's only because Ash could find the right compromise between them that he was able to win.