Plus, he has limitless spells and summons available. As long as he plans well and packs modestly, he should be pretty tough.
Limited by his MP. And you can only use a summon as many times as you have stars (I think), so you can only use a summon 5 times at most in one battle.
It's not like it really matters that much. How many times will he really need to w-summon kotr before lightning dies anyway? Let's not even get into a final attack and phoenix combo.