Yes, i never tried, but in the practice, Sephiroth its like any other character, more or less.
If you answering about copying Sephiroth's AI-controlling scripts on other characters then I agree and I think mostly the same.
For the stats, i dont know, i suppose that Sephiroth use the same curve as Vincent
Don't suppose because that supposition is incorrect.
or that information its inside the FF7.exe file
I am starting to think the same and leaning towards it but I would like confirmation. I thought that after over 25 years people found everything about this game hidden mechanics. It looks I was wrong.
Sephiroth, has some conditional restrictions that i think are in that file, for example, that you cant touch his items in the past of Cloud.
Restrictions? What do you mean by that? The only restriction I know is that stats-increasing sources do not work on him. He consumes them but they do not increase his stats. The thing you mention is not a restriction of Sephiroth. It is restriction/feature of the Nibelheim flashback sequence. It is not "past of Cloud". It is Zack's past which Cloud tells as his own. Outside of this Nibelheim flashback sequence you can touch his items and materia. But you can't do much with items other than changing Masamune for another Masamune (the only weapon assigned to him in KERNEL.BIN) and remove Tough Ring with Triangle. You can't change his armor or accessory. And if you remove Tough Ring you can't equip anything and he becomes accessory-less. It is not because of the restrictions but because he has no assigned armors and accessories in KERNEL.BIN and his only assigned weapon there is his Masamune. Other than that he also lacks some battle animations (death animation for example and for most commands) so it is sometimes funny to watch him execute some commands but he can do everything in battle (maybe except limits but his limit bar is not supposed to fill) so not restriction there again, just lack of some battle animations.