Walk on hands
Stand still, then hold Down and press A. Press A while walking on your hands to perform a super jump.
Unlimited lives
Enter the bonus stage just half-way through level 8 (Gangplank Galleon). Collect the extra life and leave the stage. Re-enter the stage to collect another extra life. Repeat this procedure to collect an unlimited amount of lives.
Code
This is a game genie code:
invincible 3E0-81B-4CA