Here are some cheats and tips for the game Marvel vs. Capcom 2: New Age Of Heroes.
Switch characters during match:
Use the following to switch between characters in the middle of the game. For
example if you choose Cable, Ryu, then Ken, but later in the second stage you
want Ryu to appear first — Hold L for the second character and R for the
third character at the versus screen.
Alternate costumes:
Highlight a fighter, then press Y or A at the character selection screen.