Please. Super-man could take every FF character that ever existed, and the summon mosnters, too.
Sephiroth is a god, Super-man is an alien.
Is there Kryptonite in Midgar? If so...Sephiroth.
If there is no Kryptonite, Sephiroth would lose.
From the looks of things, every Superman example on that site is at least 30-40 years old which tells us two things: 1) they're from a time when comic writing was typically far more outlandish and prone to making up whatever was necessary to write themselves out of whatever corner they wrote themselves into (cause, you know, the writing sucked in that Adam West Batman kind of way), and 2) none of that is in current continuity, and hasn't been in decades. In otherwords, the comics haven't featured such powers (to my knowledge anyway) in a long time.
But if you want to bring up those rediculous powers then Sephiroth would be even more screwed then he already was.