M.U.G.E.N is a fully customizable freeware 2d fighting game engine. It can be downloaded from elecbyte's website. For more on M.U.G.E.N See Wikipedia.
M.U.G.E.N already supports gamepad's however a far more effective profile can be created with Pinnacle if you Disable In Game support from the games option menu (i think that's the default anyway). The profile is set up for Player 1's Default Controls, in the way you would expect for a Class Alpha Pad. The Full Control Set is as Follows.
A = A
B = B
X = X
Y = Y
LB = Z
LT = Z
RB = C
RT = C
Back = Back (ESC)
Start = Start
D-pad Up = Up
D-pad Down = Down
D-pad Left = Left
D-pad Right = Right
LStick = D-pad