Instructions
Pause the game to bring up the map. Look for chambers that hold a yellow, glowing monster face. You need to defeat these rooms to complete the game.
Walk through the rooms in the Great Maze while looking for red doors. Stand in front of a red door and press "Up" on the controller to enter the door. Doors with a large yellow gem in the middle are used as save points and warp zones that will take you across the Maze quickly.
Enter the rooms containing monster heads and knock out the boss inside to make the icon disappear. You must thrash all of the bosses you met during the Subspace Emissary as well as evil versions of the game's heroes.
Leave the Great Maze after striking down all of the enemies by exiting the large purple door that appears in the middle of the maze. This door leads directly to the final boss in "Super Smash Bros. Brawl," Tabuu.