Asura Blade: Sword Of Dynasty Cheats

Play as Curfue:

After choosing your character, and before the map screen shows up,
hold Down and Start until the battle begins. You must hold these buttons down, before the map shows up, before every fight to continue playing as him

Play as S. Geist:

After choosing your character, and before the map screen shows up,
hold Up and Start until the battle begins. You must hold these buttons down, before the map shows up, before every fight to continue playing as him

These won't allow you to play as the bosses in a human vs human match.