This method is also easy as well. First, you go and get Anima and the Magus Sisters, then you charge up their overdrives as well as Yuna's. Then when you start the battle and you use Yuna's Grand Summon to summon either Anima or Magus Sisters. Then you use their overdrive twice since Yuna's overdrive was used. Then you keep attacking until whichever one you summoned dies,then summon the other Aeon and use their overdrive. That should be enough if you have Break Damage Limit if not, you can do what I said, then do what the others said, or summon other Aeons to finish him off. Or after you use the Aeons, just pound away with attacks with your other characters.