Cheat menu:
At the main menu enter the following(all directions on controll stick).
Left, Up, Down, A, Right, B, Start
A text box will open where you inter the cheat you want.

WHERESMAX - All models and medals.
WEWILLWIN - All levels unlocked.
MISSMACROSS - All paint schemes.

Full list of cheats
To access the cheat menu, go got the main menu and hold down L, R, and Z, then press Left, Up, Down, A, Right, B, then Start (all on the joy stick)
Codes:
SPACEFOLD: Gunpod powers up faster
MARSBASE: Missiles regenerate faster
MIRIYA: Missiles and Gunpod power faster
BACKSTABBER: Enemies are destroyed after one hit from Gunpod
SNIPER: One shot kills in sniper mode
MISSMACROSS: Unlocks all paint jobs
WEWILLWIN: Unlocks all levels
WHERESMAX: Unlocks all Veritech models
SUPERMECH: Invincibility
MULTIMAYHEM: Unlocks all multiplayer levels

Invincibility in Story Mode:
To be invincible in Story Mode, do the following:
1. Start fighter training
2. Kill ONLY 2 enemies
3. Exit training
4. Play any Story Mode mission
If done correctly you will be invincible in Story Mode

Super Veritech Armor on Ground Missions:
To use the Super Veritech Armor on Ground Missions, first go into a space mission and beat it with the Super Veritech Armor on. Then select continue. The only drawback is that the mission you use it on has to be the next mission that you go to when you select continue.... well you cant have it all.

Turn Off Cheats:
Get to the cheat menu [(while holding L R Z), on the control stick Left Up Down A Right B Start]
once in the cheat menu, input CLEAR