Bah, the only time I ever really found my teammates helpful was when facing a couple of the later bosses they would usually draw most of the fire away from me and I would get sporadically healed by one of them, but otherwise I would usually just let them die and then not bother to revive them.
And yes Sephiroth was a pain in the ass, he's not only been taking vitamins, so has his sword, the things like 20 frickin feet long, it covers over half the ring in one swipe.