Quote Originally Posted by Squall of SeeD
First of all, he still had Mako in him (look at his eyes during the close-up when Sephiroth returns), so he'd still be uber. Second, he was uber even before he was infused with Mako or injected with JENOVA's Cells. Watch Last Order. He pulled himself down the length of Sephiroth's blade and threw Sephiroth into a wall by gripping the blade; further, the wall crumpled like paper when Sephiroth hit it. Sephiroth was dumb-founded that Cloud could do this and said "What the hell are you?!"
The thing is, it's not told anywhere in FFVII when he was showered with Mako. Sure, he had the glow in his eyes, but Jenova cells could have caused that as well. Mako is given to those joining the SOLDIER, and Cloud never made it into the SOLDIER. When he killed Sephiroth in Nibelheim's Mako Reactor, I think it'd be safe to say he had neither Mako nor Jenova cells at that point. So it must have been Hojo who gave him Mako, which is quite weird when he just wanted to experiment with Jenova cells by putting them on Nibelheim's survivors.

So, yeah, Cloud was always really powerful. In any event, anyone is capable of surge in strength from the Spirit Energy. Limit Breaks/Trances are something anyone can undergo, and in Cloud's case, his Spirit Energy is just really strong.
No. The only people who have seemingly been able to reach a Limit Break are the nine party members and the kid in the inn near Avalanche's hideout. As for Trance and Spirit Energy giving you the power to reach it...

Quote Originally Posted by Sephiroth1999AD
And please, try to keep the theories and answers reasonable and within FFVII's world, so no BS things like Gaia theory, crystallized spirit energy, Jewish trees, spheres, pyreflies et cetera.