I personally haven't fought him, but he can't be as hard as most of the monsters that the Monster Trainer makes in the Calm Lands, and I've beaten almost all of the Area Conquest monsters. I just cast Hastga, come in with my overdrives full, and if that doesn't work, I just use Magus Sisters. Cindy currently has more 20000 life and Sindy's strength is maxed (255) so she always does 99999 to just about any enemy. Try to get Yuna's stats as high as possible to power up all the Aeons. Just check the 'Leveling Up' post for more info.