To randomly select a character for battle, have all characters unlocked. Press A in the space below Falco and to the left of Pichu at the character selection screen. Your hand should throw the token at random to any character.
Back to Cheats
In a Winner Out or Loser Out tournament, you can select a random character. When you are on the five by five character selection menu, hold L + R and press A. A picture of a Ditto that says random will appear. You will now play in the tournament as a random character, from out of all of the characters available on your game.