Here are some cheats and tips for the game Giga Wing.
Play as Stranger:
Enter the Gallery section and press B, X, Y, B(2), Y, X, B at the
first screen. A sound will confirm correct code entry. Alternately,
successfully complete the game under any difficulty setting without
using any continues.
Invincibility for player two:
Select two player mode, and have player one select a jet. Then,
press Start + A on controller two when selecting a jet for player
two.