MetalSora did say COM, didn't they? =.=
I dunno if you've already beaten him, but just get as many 8 or 9 lvl Cures and lots of 8, 9 and 0 lvl Key Cards. Don't bother with summons and magic.
Anyway, in the beginning, just get in as many hits on him as you can. DON'T use combos, they use up your cards faster than you can say 'I'm dead'. When he starts throwing bombs at you, and the ship starts tilting, try to dodge roll to the higher side so the bombs can't roll towards you. If you're low on health (try not to let your HP get less than 3/4 of a full bar) wait until the boat is stable again and heal. Reshuffle cards when you need to, and you should beat Hook. His HP bar isn't that long.
Hope that helped! ^^