Jikkyou Oshaberi Parodius

Invincibility:
Pause game play, then press A, Y, A, Y, A, R, L, R, L, R, X, B, X, B, X.

Difficulty 8:
Press Down(2), Up(2), Right, Left, Right, Left, A, B, X at Options Menu #1.

Round select:
Press Down(4), Up(4), Right(3), Down, Up, Left(3), B, X at Options Menu #1. The "Round Select" option will appear at Option Menu #2.

Stage select:
Press X(3), B(3), L, R, Up, Down, Up, Down at Options Menu #1. The "Stage Select" option will appear at Option Menu #2.

Nine lives:
Pause game play, then Up, Down, Left, Right, Y(2), Left, Right, Y, A, Up, Down.

Extra continue:
Pause game play, then Down(3), B, A, B, A, X, Y, X, Y, Up(3), Left, Right, Left, Right, Left, Right.

Level select:
Collect all 70 fairies.

Alternate ending:
Have a score ending with the following digits after defeating the final Boss in Round or Loop 2 or higher to have the corresponding character appear when the credits begin.

Girl on a bird: 500
Goemon Impact: 000 or 800
Gwin Bee: 700
Potted plant: 100 or 900
Red rocket: 300
Santa and a reindeer: 200
UFO: 600
Zebra on a rocket: 400