Mischief Makers
aka: Go! Go! Trouble Makers
aka: Yuke! Yuke! Trouble Makers

Sound test:
Press Left + A + C-Left + C-Right + Start at the title screen.

Bonus ending:
Achieve an "A" on every level and collect the fifty-two gold gems. Hit the target on Teren that appears during the ending sequence for a slightly different version.

Skip introduction sequences:
Press Z.