Level 2:
Hold Down on controller two, then press Down, Up, Right, Up, Left, Up, Start on controller one.

Level 3:
Hold Down on controller two and press Up, Down, Left, Down, Right, Down, Start on controller one.

Level 4:
Hold Up on controller two and press Down(2), Up(2), Right, Left, Start on controller one.

Bonus items:

Hamburger
Execute a running kit when the last two digits of the timer are "17" on level 1, "43" on level 2, and "59" on level 3.

Heart
Execute a sit-on punch on your third target when the last digit of the timer is even.

P power-up
Execute a jump kick when last two digits of the timer are "32" on level 1, "25" on level 2, and "11" on level 3.