Final Fantasy XIII
My advice, which is difficult because I forget the names of everything:
You know how you can use an item to cloak and be hidden from enemies? Use the one that gives you Haste and some other bonuses.
You want a Com/Rav team of Hope and Lightning, and alternate to Rav/Rav whenever the boss is Staggered.
If the boss is Staggered and weak to Lightning (uses water attacks), have Lighting summon Odin, and just relentlessly attack it, and be sure to finish with a powerful attack.
If it's still not dead, Com/Rav and remember to keep healing.