Instructions
Wii Remote + Nunchuck or Classic Controller
Turn the Nintendo Wii on. Remove the battery cover from the back of the Wii remote. Insert two AA batteries.
Open the SD card cover on the side of the Nintendo Wii and press the "SYNC" button. The sync light on the Wii will begin flashing. Press the "SYNC" button under the battery compartment on the Wii remote. Lights on both the Wii and Wii remote will flash and eventually stabilize. When they are solid, this indicates that the Wii remote has been synced to the Wii. Repeat these steps one at a time for each Wii remote you intend to sync.
Replace the battery cover. If applicable, insert the Wii nunchuck or either classic controller into the expansion slot under the Wii remote.
Select the animated "Brawl" icon from the Wii Channel Menu to begin the game. From the character select screen, scroll down to the CPU icon under the character box. Press the "A" button to enable a second player. You can toggle to or from the CPU (which indicates a computer controller character) or any player (up to four) under all of the character boxes.
GameCube Controller
Open the GameCube controller bay on the side of the Nintendo Wii.
Insert up to four GameCube controllers into the ports inside the GameCube controller bay.
Select the animated "Brawl" icon from the Wii Channel Menu to begin the game. From the character select screen, scroll down to the CPU icon under any character box. Press the "A" button to enable a second player. You can toggle to or from the CPU (which indicates a computer controller character) or any player (up to four) under all of the character boxes.