This is the best save file possible for Aero Fighters Assault! Both Mao Mao and Spanky the dolphin are unlocked for use. In addition, the game has been completed up to the fourth bonus stage, the game's true final stage, to allow for the use of all playable enemy fighters in Deathmatch mode.
Note that continuing the game and beating it will remove the enemy fighters from play in Deathmatch mode!
To freely enjoy the game's single player stages without losing the enemy fighters, enter this stage select cheat during the game's intro after the fighter jets appear but before the title screen appears: D-pad Up, Down-C, D-pad Left, Right-C, D-pad Down, Up-C, D-pad Right, Left-C, L, R, Z.
If successful, you'll hear a "howling" sound effect. The Continue option will be unavailable, but selecting Main Game will allow you to play any of the game's stages, including bonus stages. This does not affect the game's save data.