i really dont remeber the 6 buttons on the Genesis , same as saturn 
The 6 button controller for the Genesis was introduced back when Street Fighter II was all the rage. Back then a lot of systems started to get 6 button controllers as soon as Street Fighter II was ported to their systems: PC Engine, Genesis. Other systems had controllers were buttons were moved to a more appropriate postition for playing SFII (3D0 and SNES got their shoulder buttons repositioned as face buttons, etc.)
I don't think that the 6 button Genesis controller matches the 6-button CD32 pad button configuration. I've got both, so I guess I can try it out if anyone is curious.