At the Press Start screen press A X Y Z C B. On the next screen go to Options and hold R then press A.
Play as Repli and Wolf
At the Press Start screen press A B Z X Y C.
Play as Sho and Vermillion
Enable the code above Play as Repli and Wolf and wait for the tone. Now press A Z C X B Y.
Enter the two codes above then press A Y C X B Z. Press C Z while playing to do the secret move.
When Start is flashing on the Title screen press A B C C C X Y Z Z Z. Press Start and highlight 1P game then hold R Y and press Start.