Instructions
Open the side compartment of the Wii that has the controller sockets. Plug GameCube controllers into the Wii controller sockets. The "Player 1" socket is closest to the "Power" button and the "Player 2" is right next to the "Player 1" socket."
Insert the GameCube disk into the Wii console.
Click on the game's icon from the Wii's main menu to launch the game. Press the "A" button on the GameCube controller to have the Wii recognize it as the default controller. The tops of each side of the GameCube controllers are "Trigger" buttons if you need to fire for a game. It has "A," "B" and "Z" buttons, which can be used for different reasons depending on the game type and game instructions. You can also use the joystick and directional pad on the left part of the controller to move the character you play.