Unlock every character in multiplayer by inputting this code:

Hold L + R, C-Left; Hold L, C-Up; Hold L + R, Left; Hold L, Right; Hold R, Down; Hold L + R, C-Left; Hold L, C-Up; Hold L + R, Right; Hold L + R, C-Down; Hold L, Down.

If you pick Oddjob you are a cheater and no one likes you