To put it in a less blunt way...Isa is really, really damn hax. Let's put it this way: he takes a dive into a planet that is almost all lava and is unharmed. He goes on to fight not one, not two, but FIVE huge, spacefaring foes, and trashes them. He's absolutely ridiculous, downright monstrous even. Fou-Lu is good, but even in his boosted mode he's still a couple notches below that much power. Fou-Lu can probably keep him busy for a while, but won't come even close to winning or even doing all that much damage. Isa requires a double or triple team to beat - the question is if Drak's team can deal with the rest of the team fast enough to win, because not a single one of them can beat Isa alone, even if buffed to the gills.
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Currently playing: League of Legends, Chrono Cross.
Current Projects: Fool's Overture, CYOA: http://www.gamefaqs.com/boards/8-gamefaqs-contests/60143513