Make sure you have a good team of monsters too.
I think I had a high level Green Chocobo (medic), Blue Chocobo(ravager), and a Dreadnaught (commando) the first time I beat it. There are some really good guides on how to optimize your monsters by mixing abilities of other ones. If you max out one of those medic flans, and mix it with your Chocobo, you've got a pretty good healer right there.
The Dreadnaught's a little slow for the final boss, but he's got a ton of HP, and hit's pretty hard.
A good sentinel monster might be a better bet for your setup, but much like the final boss in FFXIII, it makes things a bit easier on you if you're more aggressive.