Which main series final boss would win . . .

[Rez09]

In an arm wrestling contest?

[Sephiroth]

Pure physical power - Bhunivelze. Or Kuja. He is a SSJ4.

[Omni-Odin]

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or this

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[Rez09]

I feel like Zeromus vs. Braska's Final Aeon would be a hell of a matchup.

What about Emperor Palmecia?
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Bro doesn't seem to have legs and it must've taken some serious upper body strength to drag himself out of hell. ;)