anima doesn't counter attack so you just quick hit over and over and over and over. when you see his overdrive fill summon an aeon... piece of cake. Bahamut though will try to sneak in an overdrive when he randomely counters coz it fills his gauge up fast when he hits your whole party for good damage. so you have to be careful and not attack him when his turn comes close and his overdrive gauge is moderatley full.... can be tricky. And after surviving his counter attack, whatever you are hit by next will kill you because of armour break. i just found the battle with bahamut required a little more thinking than the others