To be completely honest, I found Sephiroth waaaaaaaaaaay easier on this game than on the first Kingdom Hearts. And when I say waaaaay easier. I mean it. I remember NEVER clearing the first Sephiroth battle. But the KH2 version? Pfft. A breeze, walk in the park, and piece'o cake. 8)
I can relate to that.
I mean, I did also beat him in KH1, but hell, his katana filled the whole fucking stage. Even though it was possible to use Curaga like a million times, that fight was HARD.
While in KH2, you just shouldn't do any stupid moves and you're fine. AND FUCKING UNEQUIP DODGE SLASH BEFORE EVEN TRYING.