In Super Street Fighter 2 (AGA) you need to go to the options screen and choose 2 button joystick else it uses its default 1 button setup.
I don't know about the other versions of Street Fighter 2 as I only play this one on the Amiga.
Some other games need setting up in options whilst others support 2 buttons by default. Some games even if you have a 2+ button pad only one works
Steve.
