Cause between me an squenix, one of us actually care about it's characters. :p
And if we are just tossing Logic out the window, Kuja and Kefka would rain untold amounts of hell.
I was originally going to say Seymour and Sephiroth. They both want to destroy the world, so let them do it together (and kick Cloud's and Tidus's butts simultaneously while they're at it) (j/k, I love Cloud and Tidus :-/).
And then blackmage reminded me of Emerald and Ruby Weapon. Yes, they're from the same game but just imagine fighting them together.
If you did actually imagine it, the next time you start up VII and load your game, you will get instant game over because even the IDEA of this combo has that much power. :exdee: