Play as Tekken characters:
Highlight the "Start" option at the title screen and hold Left + X + Circle + Start on controller one to transform the ship into Heihachi. Hold Right + X + Circle + Start on controller two to transform the ship into Paul.

Five continues:
Highlight the "Xevious 3D" option. Hold L1 + L2 + R1 + R2 and rapidly tap Circle at the game selection screen.

Debug mode:
Press Square + X + Start at the Xevious title screen. The original Xevious game will begin in debug mode.

Black ship:
Highlight the "Reset" option at the title screen. Hold L1 + L2 + R1 + R2 + Start. Press Start after the "Start" is highlighted and hold all buttons until the ship transforms.

Wide ship:
Enable the "Black ship" code. Return to the title screen and highlight the "Exit" option of the configuration mode screen. Hold L1 + L2 + R1 + R2 + Start. Press Start after the "Start" is highlighted and hold all buttons until the ship transforms.

Twisted ship:
Twist the NegCon controller to also twist the ship.