1st time: Automatic Radar

2nd time: Ability To Throw The Laserblade

3rd time: Have Heat Taken Away From Attack

4th time: Ability To Walk While Shooting Back Weapons

5th time: Use Half Of The Energy

6th time: Double energy

Steal Your Enemies Emblem
In the single player Arena mode you can steal your defeated opponent's emblem. To do this you of course have to beat an opponent in the Arena, then once beaten you can go back to the opponent selection screen where everyone is ranked by number. Highlight and select someone you have defeated and then press START + SELECT and you should hear a sound. Press the two buttons again and again until you hear the sound. Once you hear the sound go to the Edit Emblem screen and the emblem selected will be the one you just took from your opponent. You can then edit it or just wear it as your own.

Use overweight AC Units
Once you finish the entire game the first time and you see the credits, the next time you start a game using the final save (the one you make after the credits) you can buy equipment and parts that would normally make your mech overweight. You will then be able to use your overweight mech the next time you play.

Debt of 50000:
You have to go in debt of 50000 six times to unlock these cheats:

1. Automatic radar
2.Ability to throw laserblade
3.nothing that i know of
4.shoot back weapons while walking
5.nothing that i know of
6.double energy

Easy way to win in arena:
If you are having a lot of difficulty in the arena, there is an easy way to beat just about anybody. It helped me get all the way to rank 9. There is a level you can choose in which you start off on top of a tall building, if you just sit there, then the enemy usually flies out of the ring.

Secret Weapon:
The weapon is hidden in the mission against Emeraude to destroy the surface weapons. Right when the mission starts, fly over the surface weapons and look over to the rocks where there is a small hill. Somewhere around there lying down is the karasawa mk-II(the weapon one the AC has on the cover). Press circle to pick it up. This is a laser weapon that is extremely powerful with 50 ammo. I think it is one of the best weapons in the game.

Another way to win arena:
The way to do it is to buy the back part that shoots 2 multiple warhead missiles its expensive but you'll make it. Then go to the Etal Base and from the beginning fly to the platform all the way in the air and then there is a pole in the middle. Fly on top of that. That's all use the multiple warhead missile and no matter where he is they can track ure enemy.

During gameplay, press L2 + R2 + R3 simultaneously. If you entered the code correctly, a "Limiter Released" system error message will appear, and you will have infinite energy during this time. After approximately one minute, the "OB Down" system error will appear. It will last as long as the previous error, but you will not have any energy. After "OB Down" is completed, your AC will recharge and return to normal. Make sure you finish off your enemy before you become vulnerable.

Load Info From Original AC2:
Load your saved game from the orginal Armored Core 2 game into the One Player Scenario to start where you left off before the expansion. This, of course, hinges on the fact that you played and saved a file from the original.