Ninja Turtles 4: Turtles In Time

Level select:
Highlight the "Option" selection at the title screen, then quickly press Up(2), Down(2), Left, Right, Left, Right, L, R on controller two.

Ten lives:
Highlight the "Option" selection on the title screen.
Quickly press Up(2), Down(2), Left, Right, Left, Right, B, A on controller two, then Start on controller one.
The "Rest" option on the options screen may now be set to ten.

One player extra continues:
Press Start on controller two just before losing with no continues remaining.
Game play may be continued as player two with the continue total reset to full.

Alternate music:
Enter sound test mode from the option screen.
Set the sound test to the "Staff" selection, press B to play the song, then press Y.

Hint: Extra points:
Throw your opponents at the screen for more points and lives.