Invincibility
Begin a new game and immediately press B, A, B, Start, Up, Down. Your character will now be able to pass through all opponents except for Bosses.
Special Passwords
These passwords let you play through just the even stages or just the odd stages.
To play the even stages - A 2 A 4 A 6 A 8 A 0
To play the odd stages - B B A 1 3 5 7 9 1 2
Final Boss - E3D3D 3D3DF
Final Boss and Invincibility - __135 79BD_
Start With Max Power and Speed
In the flight worlds with bosses, such as 2-1 and 4-1, just before the level starts there is a brief pause where you stand on the entry door for a few seconds. In that time, hold Select and press Up, Down, Right, Left to begin the level with max power and speed.
End level...