Well If he did destroy the solar system, he wouldn't become a 'god'...it would beat the purpose.ChrisFFfan, let me put it to you in the simplest way possible.
Edea=Not the villain of FFVIII. Ultimecia controlled Edea's body.
Ultimecia=The villain of FFVIII and a horrible one at that.
And One Winged Angel Sephiroth:
You honestly have very weak support on why Sephiroth is great. Burns down Nibelheim, kills Aeris and President Shinra, manipulates Cloud, and summons Meteor so he can become a god. Nobody who played FFVII before wouldn't already know these things.
Being in more than one game....you must be kidding me. That is completely irrelevant to how great a villain he is. I think he is in FFVII Before Crisis and Crisis Core, though we can't judge those, since we don't know what he is like in those yet. In Kingdom Hearts I, he was just an extra boss to fight, and in Kingdom Hearts II, he was just Cloud's enemy; and they have a fight scene and that's the end of that. Finally, he's also a secret character in a game called Ehrgeiz, which is some fighting game somewhat like Tekken I've heard. These games really only show how overrated he is and has too many fanboys/fangirls who like him for no good reason. Some of them are like you, actually.
"You have to beat him more than once"
I'm guessing you are supposed to show his power by giving this as an example. Well, first of all, using battle mechanics to determine a person's power is totally inaccurate. And if Sephy could really destroy the Solar System, he would already be a god, and wouldn't need Meteor to do his work for him.
There are people on this forum who give much better support for Sephiroth than you. While I may not agree with them sometimes, at least they know how to back up what they say.