Mighty Morphin' Power Rangers

Cheat mode:
Press Right, A(2), B, Start at the options screen to unlock the "Invincibility" and "Level Select" options.

Secret Power Ranger:
Press Up, Down, Right(2), Left when Lord Zedd drops down at the end of level 1. Then, press A(3), B(3), C(3), Start to unlock Gold and Silver Power Ranger and receive 10,000 points.

Evil Green Ranger in two-player mode:
Press A + B + C repeatedly on controller two at the Banpresto logo screen. A voice will shout ''Power Rangers'' will confirm correct code entyr. The ''Evil'' version of the Green Ranger should now be selectable in two player battle mode.
Information in this section was contributed by naomi morinaga.

Hint: White Ranger:
Successfully complete the game under all eight stars of difficulty to unlock the White Ranger.
Information in this section was contributed by Jab4reel.

Hint: Level 3:
An easy way to complete level 3 is to use the Red or White Ranger.
Information in this section was contributed by antoine cook.