Fight as Bosses:
Press Select, A, Up, R, Up, Select at the title screen. A ringing sound will confirm correct code entry. Hold Select + R when entering the character selection screen to fight as Neo Geeguse. Hold Select + L when entering the character selection screen to fight as Dio.
Hint: See all endings:
Complete the game without losing with anybody on the number 4 hard difficulty setting, no time, and normal energy bar. Then, go to versus battle mode and choose the character whose ending you wish to see. Then have player two select anyone. When the battle starts, defeat player two in both rounds. After it shows both players’ winning stats, the game will display the ending for the player that won. Do not allow the game to idle too long after your win or it will enter demo mode and you will have start the trick again. To see another fighter’s ending, keep selecting the player whose ending you want to see in versus battle mode until you have viewed all the endings.