1) Yu Yevon
2) Final Fantasy X
3) He's ridiculously weak and even casts auto-life on you
4) about 10 seconds I guess
5) One perfect attack reels from Wakka WITHOUT break damage limit killed him. Does this count as an OHK? I'm tempted to say yes.

I woulda said Sephiroth but I really don't count that as a fight since no matter what you'll attack Sephiroth and win. Yu-Yevon is similar, but I think that if you worked at it hard enough you could find a way to lose to him (it?).