Okay, Crystal, hypothetical question. If Sephiroth achieved his full potential, would he be a threat in other universes (Ex. Marvel, DC, etc.)?
No.
He'd be annihilated by any top tier hero with ease.
God forbid Superman wants him gone.
can be stupidly fast(like Omega Weiss and Chaos Vincent that were fighting like the DBZ characters)
No. He's bullet-time speed at best. ALl he showed = all he can do.
I won't give him speeds he never showed nor said he could do.
can move a friggin planet across the universe,
Never did it. Was defeated by an emo punk.
Post-Nibel Sephiroth is in a completely different league than Akuma.
Can he destroy islands with one punch?
Can he send peoples souls to Hell?
I remember him having a swordfight and losing. That's about it.
Hell, Akuma's most powerful attack is said to be capable of destroying an entire continent by SFIII.
Seph was defeated by Cloud's Omnislash. That attack is not island-sinking level. So, Akuma destroys him with one punch.