Firstly when you have the chance to prepare before the fight, give your guys skills like jelly, and locomotion, so they can survive grand cross a bit easier. Having lot's of quick remedies also is very helpful to get back up. Hasting people helps, but for the most part just keep your HP up and bash him with strong attacks before he get's shell and protect on and he shouldn't be much of a problem. Also getting to about level 60+ will make the fight easier by a good bit. Mid 60's work best I found. Also if you have the rebirth ring, mastering auto life is very helpful, and auto regen helps out quite a bit.