Begin a normal game and play until you're defeated and have no credits left. Before the time
runs out, press Start on Controller Two, then quickly press Start on Controller One. Select your character with the B button and your credits will increase to 99.
Play as Same Character
As the Capcom logo fades, quickly press Down, R, Up, L, Y, B, X, A before the logo fades. If you did the trick correctly, the screen will flash blue and both players will be able to select the same character.