1. Unlock SOnic and Snake 2. Beat 5 characters in Cruel Brawl with Both of them. 3. Next beat Classic mode 10 times without taking any damage on intense, until you reach Master Hand. 4.Play Subspace Emmisary and beat Tabuu 100 times on intense 5.After that, play Multiplayer, and switch everyone's colors 73 times. 6. Then use Cpt. Falcon over 1000 times. 7. After that you'll unlock the "Hard Core" difficulty, then play it on classic 20 times, with out dieing. 8.Then you'll unlock new Alt. Costumes for EVERY character. 9.Go back to multiplayer and switch colors for costumes 100 times each costume. 10. Go back to SSE, and beat Tabuu. 11. He'll chalegne you, after you beat him, and you'll be able to unlock him from there.
The third way is to play SSE using a DDR pad. When you get to Taboo, the final match is a danceoff. Lose, and he'll determine that you stink so bad at dancing he'll join your team to make fun of you every freakin second.
To unlock him, you must beat Classic with all 38 characters and then you must beat Adventure Mode (not SSE) with Captain Falcon and Pichu teamed up. After you beat Eggman in Adventure, you must get an EyeToy into the USB slot in the next 5 seconds. After that, you must do a Falcon Kick and SHOW THE GAME YOUR MOVES. After that, you can fight Tabuu, but you must use Pichu with your eyes closed. If you don't, the EyeToy will catch you and kill your Wii.