If you are an Aeris lover: If you leveled her up put the most powerful summons on her + Restore-All + Enemy Skill (Big Guard) + Cover. If you managed to get her to at least Limit level 3 you're safe. If not no prob. Also note that that her Ultimate weapon is in the Temple of the Ancients.

If you dislike Aeris: Use Yuffie/Red XIII as healers and Cid/Barret/Vincent as attackers. Try to get to Limit level 2 or 3 and you'll be doing just fine.

Other tips: good place to level up, Mideel Area (green area); Wutai Area. Try to keep your characters HP above 500 and you'll be fine.

Fastest way to kill him: Cloud's Meteor Rain killed him in one turn (for me)