Yoshi/Kamek
abstain
Pokemon Trainer Red/Pokemon Trainer Blue
Big Boss/Revolver Ocelot VS Solid Snake/Revolver Ocelot
Raziel/Kain
Gordon Freeman/Dr. Breen
The Nameless One/The Transcendent One
Captain/CATS
Fox McCloud/Wolf O'Donnell
Kasumi/Ayane
Sora/Riku
abstain - don't recognize either
Tifa/Aeris
Balthier/Dr. Cid
Tom Nook/Crazy Redd
Vyse/Galcian
Lucas/Claus
Wheatley/GlaDOS
Seigfried/Nightmare
Liu Bei/Cao Cao
Yuna/Seymour Guado
Squall Leonhart/Seifer Almasy
--
Nominate Balthier/Dr. Cid for the Greatest Game Rivalry Contest
Also Tidus/Jecht, Squall/Seifer, Sora/Riku... but mostly Balthier/Dr. Cid :)