What worked for me was:
Have overdrives for everything (aeons and characters), but don't use them early on in the fight. Knock him down to about 30,000/40,000 HP without them, then start to hammer him with everything you have at 30,000. Apparently the slower you lower his HP to 30,000 (when he can use 'total annihilation'), the slower he is to use it. This sounds strange but it worked for me, give it a try.