To choose your alternate paint job in Main Game, Practice or Boss Attack mode, press the R button at the plane select screen.
To select the alternate color in Death Match, hold the R button while selecting one of the four original planes.
After completing every level (including the bonus levels), you go to a new level -- the Moon. You will have no wingman support though.
At the "PRESS START" screen, press C-Left, C-Down, C-Right, C- Up, C-Left, C-Right, C-Down to get a bonus plane
Beat the first two stages to earn the MIG 25 and MIG 31 bonus planes. Complete the third and fourth stages to earn the F-22 and KFR C2 bonus planes. Finish the game to earn the EFA and RAFALE bonus planes. They will appear in the battle mode.
Enter this code at the title screen to get the lady pilot in the F-15: C-Left, Down, C-Right, C-Up, C-Left, C-Right, C-Down.
To have a level select, press the following (use the cross-pad): Up, C-Down, Left, C-Right, Down, C-Up, Right, C-Left, Z, R, L. This will enable all levels to be played regardless of where you are in the game.
To play as Mao Mao, when the screen says "Press Start Button," enter the following: C-Left, C-Down, C-Right, C-Up, C-Left, C-Right, C-Down. He'll appear at the pilot select screen.
To play as Spanky, complete all three of the bonus missions.
Choose the F-14 then start a new game. While flying, use your special, missile and chaff (in that order). If you did it right you'll launch five Tomahawks and four heat-seeking explosives.