Always have F-15J
Always have X-29A
During the intro scenes (when you see the jets fly) enter the
following code: Up (D-Pad), C-Down, left,
C-Right, down, C-Up, right, C-left, L, R, Z.
You should now hear a chime to tell you the code worked.
Now select Main Game and pick the mission you want --
from Tokyo to Space.
Play as Mao Mao
Wait for the words "Press Start Button" to appear on the tittle
screen then press C-left, C-down, C-right, C-up. C-left,
C-right, then C-down, at the "Pilot Select" screen. You will
now be able to select Mao Mao and her F-15 (you may
have already gained access to Mao Mao if you continued
more than three times in the Tokyo stage).
Play as Spanky
If you complete all three bonus missions, you can play as a
new character: Spanky. No, we're not kidding.
Don't like the look of your plane? Simply press the
R-Button at the plane select screen to bring up an alternate
Extra Pilot and F-15
At the title screen where it says "Press Start," punch in the
following button combination: C-Left, C-Down, C-Right,
C-Up, C-Left, C-Right, C-Down. You will now be able
to fly a new F-15 plane, complete with a new pilot.