Burning thought
Restricted
okie looking through the videos ive scrapped together as much as i can understand of what hes doing, and ofc reading what Wandering flame says he is doing
fight one final mix encounter
i think kain would take this easily, Xemnas does not move as quickly in this as he does in the other battles, he uses an impressive variety of energy attacks but they would not avail him, Kain can also control energy so many of the non beam attacks Kain could reflect but he could win this with simple use of TK and perhaps a few Soul reaver swings, single time bolt early on before Xemnas can do much, did he teleport in the first battle? ime not so sure but regardless kain could take this without too much difficulty
fight two initial KH 2 fight
similiar in this one, Xemnas seems to be a bit quicker and like before has diffrent shields to make himself invulerable but a time bolt, time powers, TK will mess him up a bit, being pulled into the air or shackled in place so you cannot attack is a often disabilitating thing, then gets time frozen or reaver slashed
fight 3, second to last battle
i think as awsome as that enormous dragon machine looks, it will be a hinderence, theres no way Xemnas (hes the guy in the armor i guess?) is going to have a chance just sitting on that seat, since he does not get up or anything in this battle it would be easy for kain to destroy him with reaver/time bolt, the machine will be a hinderence because if Xemnas closes it up, Kain could easily teleport to stay inside, or escape the hit that knocks Sora and Riku away, or shield himself, also this phase will be easiest mainly because there a lot of times where kain will not be hit, and can use various powers quickly
final fight
most difficult of all, kain may actually have a fight on his hands since Xemnas is quicker than ever, uses a lot of blasts, if kain lets loose time powers he can win but not as easily as the other battles, if he doesnt use time powers he can use Tk to throw Xemnas around, use immoalte to explode Xemnas from the inside, or soul reaver slice, this fight showns xemnas with what seems to be even more energy attacks. Kain can also shield to escape damage.