Extra Characters in Multiplayer Mode
Select a file and choose Multiplayer mode.
(You must have at least two controllers
Plugged in to access this option.) When the
Multiplayer Options menu appears, choose
"Characters," then enter the following code
at the Select Character screen:
1)Hold L+R and press left-C
2)Hold L and press up-C
3)Hold L+R and press Left on the D-pad
4)Hold L and press Right on the D-pad
5)Hold R and press Down on the D-pad
6)Hold L+R and press left-C
7)Hold L and press up-C
8)Hold L+R and press Right on the D-pad
9)Hold L+R and press down-C
10)Hold L and press Down on the D-pad
If you entered this code correctly, you will 
have a total of 64 playable characters at the 
Select Character screen.