Mother Mosquito

Hold L1 and press Up, Right, Left, Down, Square(2), R1(3) at the character selection screen. If you entered the code correctly, you will hear a shout.

Father Mosquito

First you must enable the "Mother Mosquito" code. Then, hold L2 and press Up, Right, Left, Down, Square(2), R2(3) at the character selection screen. If you entered the code correctly, you will hear a shout.

Two Player Mini-Game

After turning the screen on hold Start + Select. Press Square to move forward, X to jump, and Triangle (when the power meter is full) to do a super attack. Alternately, hold L2 and continuously rotate the Right Analog-stick clockwise at the title screen