Ozma wasn't as hard for me at the time I fought him. Meteor doesn't do damage to the party unless you're referring to doomsday. When Ozma does cast it you can prevent him from healing himself by casting curse on him until he's weak to shadow so he'll get hurt by his own attack.
For me it was Omega Weapon in VIII and the final boss in Chrono Trigger. One hit with either one of them and by party was dead.