Unlimited Soul Bombs
Press Start to pause a match. Use the controller configuration option to map the L1, L2, R1, and R2 keys to Soul Bombs. Resume game play and press one of the those buttons and X simultaneously to release a Soul Bomb. That button combination may be pressed an unlimited amount of times during the match.
Instant secret moves
Beat the game with Naru, then set two or more of the shoulder buttons to special moves. Press all special move buttons at once to perform a secret move. Note that this does not work for all characters.