Metal Slug X cheats and cheat codes for Playstation

Mission select and another mission modes:
Finish arcade mission mode to access mission select in arcade mission

Chat with the instructor
Choose the Combat School and while it is loading, rapidly press 
Square until the menu appears. The instructor will ask if you want 
to chat with her.

Combat School ratings:

Reach more than 100 points - Private Rank
Reach more than 150 points - Private 1st Class Rank
Reach more than 200 points - Corporal Rank
Reach more than 250 points - Sergeant Rank
Reach more than 300 points - Staff Sergeant Rank
Reach more than 350 points - Sergeant 1st Class Rank
Reach more than 400 points - Master Sergeant Rank
Reach more than 425 points - Sergeant Major Rank
Reach more than 450 points - Warrant Officer Rank
Reach more than 475 points - Chief Warrant Officer Rank
Reach more than 500 points - 2nd Lieutenant Rank
Reach more than 550 points - 1st Lieutenant Rank
Reach more than 560 points - Captain Rank
Reach more than 575 points - Major Rank
Reach more than 600 points - Lieutenant Colonel Rank
Reach more than 650 points - Colonel Rank
Reach more than 700 points - Brigadier General Rank
Reach more than 780 points - Major General Rank
Reach more than 890 points - Lieutenant General Rank
Reach more than 990 points - General Of Army Rank
Reach more than 1000 points - Super Devil Rank

Metal Slug X Game Shark Codes:

Unlimited Time
8002962A 2400

Unlimited Arms Ammo
8002DCE6 2400

Unlimited Bombs
800398BE 2400

Unlimited Lives
80047522 2400

Maximum Score for Player 1
800EE290 FFFF

Maximum Score for Player 2
800EE298 FFFF

Extra Prisoners Player 1
800879EC 00FF

Extra Prisoners Player 2
800879F0 00FF

Invisiblity for Player 1
800CA30C 0068

Invisiblity for Player2
800CA458 0068

Unlimited Vehicle Health 
80053F7E 2400