Things You'll Need
Instructions
Start the game and press the "A" button on your Wii remote to enter the main menu of the game. Move your Wii remote pointer to the "Classic Mode" option and press the "A" button.
Select the character you want to play as and defeat each level in Classic Mode. Select "The Subspace Emissary" option to play in the storyline mode.
Complete the storyline mode, and defeat the Winged Tabuu character as the final boss. Once "The Subspace Emissary" mode is complete, the "Boss Battles" mode will be unlocked.
Select the "Boss Battles" mode from the main menu and select the first playable character. Complete every boss battle in the mode.
Play the "Boss Battles" mode again and complete the mode with every character. A pop-up message will then appear that says Tabuu has been unlocked.