Parodius
All items
Pause game play and press B(2), X(2), A, Y, A, Y, Up, Left.
Invincibility
Pause game play and press L, R, Up, X, Right, A, Left, Y, Down, B, A, Y, A, Y, R.
Three smartbombs
Pause game play and press X(3), B(3), Y(3), A(3), L, R.
Level select
Press Up, Right, Down, Left, X, A, B, Y at the options menu.
Auto-pilot
Pause game play and press Up(2), Down(2), L, R, L, R, B, A.
Difficulty 8
Press Up(2), Down(2), Left, Right, Left, Right, B, A at the options menu.
Highlight Octopus at the character selection screen then hold Up + L + X for approximately 30 seconds. A new menu will appear, with options for level selection, scene selection, and Mutek. Note: Set "Mutek" to "01" for a fully powered up and invincible ship.
Control red octopus
Wait until the penguins that located before the red octopus appear. Stop, then press Up + L, B(5), Y(5), A(5). When the red octopus appears, press A + Y. The position and size of the red octopus may now be changed with the D-pad.
Disable cheats
Pause game play and press Up(2), Down(2), L, R, L, R, B, A.
Self-destruct
Pause game play and press Up(2), Down(2), Left, Right, Left, Right, B, A.