Sephiroth vs Akuma - Sephiroths a queer sissy boy. End of story.
Cloud Strife vs Ryu (Capcom's Street Fighter games) - Undecided, KOTR vs Hakuden.
Zack vs Kyo (SNK's King of Fighters games) - Zacks the real deal, not a cheap imitation *cough*Cloud*cough*.
Vincent Valentine vs Batman - Batman is a tard and would probably shoot himself in the foot.
Yuffie Kisaragi vs Kim Possible - Doom of the living, versus some black guy on a handheld giving you all the answers.
Tifa Lockheart vs Captain America - Tifa would suffocate him with her cleavage.