Check out this high level battle between the Onion Knight and Jecht
YouTube - Onion Knight (lv. 74) VS Jecht (lv. 74) FF: Dissidia

Or even this high powered battle between Terra and Sephiroth.
YouTube - Terra Branford (lv. 52) VS Sephiroth (lv. 52) FFissidia

And all I have to say to this one is...DAMN!
YouTube - Dissidia Cecil vs Golbez