What FF Villains Could Beat Sin?S

[PuPu]

As for Machines who could destroy Sin, either SHINRA's military cannon or FFXII's Bahamut.

By SHINRA's military cannon, do you mean the Junon Cannon or the Sister Ray? Junon cannon is a no. Sister Ray probably could though, since it skewered Diamond WEAPON and destroyed Sephiroth's barrier.
Also, I still don't understand your argument or proof as to how Sky Fortress Bahamut could defeat Sin.

But what should have been written is if another vilain could overpower Sin in versus Combat. Based on Size and force display abilities without the game mechanic of battle of the game.
Then, I'd say no to maybe.

Aren't you the one who said Ultimecia could just reduce Sin's HP to 1?
Besides, Giga Graviton is not just battle mechanics. We've seen Sin use it outside of battle and cause lots of destruction with it. Ultimecia's Hell's Judgement only appeared in battle, so it's power can only be judged by battle mechanics.

'oh and by the way, there attacks proved to be one hit kills too'

What proof? The fact that they can kill something in one hit does not mean they can kill anything in one hit.

Even if Sin dies, it will be reborn again.

But I thought that Sin only gets reborn if you use the Final Aeon to kill it?

Other villains are very small, compared to Sin. So none of them can beat Sin, it would be a miracle if they did.

Size doesn't really doesn't have that much influence on power. After all, Yu-Yevon himself is pretty small too.