The Classic Controller is a special controller attachment for the Wii Remote. While it is compatible with any Virtual Console game, it is heavily designed after the SNES controller and Sega Genesis controller. Many Wii games can also be played with the Classic Controller.
Classic Controller Pro
The Classic Controller Pro is an updated variant of the Classic Controller. It features grips, much like the GameCube controller, and moves the cord from the bottom of the controller to the top, making the cord a little bit less bothersome. The Pro is also larger, reducing the cramped feel of the controller.
The grips, however, remove the controller's SNES/Genesis like feel. It was released alongside Monster Hunter 3 as the controller of choice.