I would just hack away at him, i hardly ever use any magic ( that includes stuff like ragnerock ) just a cure here, and an areo every once in a while, if in real life I was as strong as the sora that I have on my most recent save file, I wouldn't have a problem, his strenth is at 90, and I'm not at lvl 100 yet so I am betting that it will go up one more time, and I plan to use a few more power ups on him, so yeah, i would just swing wildly