Samurai Shodown 2
My buddy and I play the hell out of that game whenever we can steal a few minutes.
Personally I'm a street fighter fan myself. SFA3, Marvel Super heroes vs. Street fighter, Street fighter 2 X: The Grandmaster Challenge.
Oh and the SF Anny collection is a Playstation 2 game with a new Variation of Super Street fighter 2 called Hyper Street fighter 2 and it comes with Street fighter 3 Third strike. I can't wait to get this. It came out this week but I'm moving so I haven't had time to pick it up.
-G