Go buy the CLASSIC Wii Controller.. Its the SNES looking gamepad that you can plugin to the wii remote. It will register perfectly.
I use the wii remote itself for NES games, and the classic controller with all the extra buttons for genesis, snes, and soon PSX
I also use the z1 and z2 buttons for Save state and load state.. Comes in handy if you are playing action games and easy way to cheat if you save right before a hard part