Invincibility:
Enter H800 lbW2 kG4Q KwKc 66WH QbW2 0F1D G19D as a password.

Ending:
Enter yDaB pc71 jQOA uT3D nfWW 3UKT Yv4g G5WH as a password.

Alternate ending, C.O. lives:
Enter WL8k Xv57 TwOB WU3C BDA7 cvJ7 2PtH 9EO4 as a password.

Extra lives:
Enter 0000 0000 0000 0000 0000 0000 0000 0000 as a password after completing the game. Defeating a Boss in the next game will result in extra lives.

Teleport:
Stand on one of the "N" and "S" indicators that appear on the ground and press Up.