Tip 1: A little ways into the game there is a mission to guard a train that is carrying a newly developed AC part, destroy the 2nd to last box car on the train and you can steal the part.

Tip 2: On the "Rescue Research Team" mission with all of the disorder units there is a transport that takes you from the first large room to the second large room, when you get on the transport jump off and about half way in between the rooms there is a hexagon that is colored black and doesn't fit in, shoot it and fall down into the room below for an AC part.
Send in by Bfarn27@aol.com

Infinite Energy:  
Sent by KiwiLaser Hranchook@home.com
When in any point in the game (anytime in split screen vs. or in single player) just simultaneously push L2+R2+Over Boost button. It will give you infinite energy until the match or mission is over then it needs to be repeated. When you wish to undo the cheat just repeat the process.

Hidden part:-  In the training room, if you shoot the circle in the ceiling enough, it will break, revealing a secret area. You need good boosters or a light-weight AC to get up the shaft into the area, and when you do, you will find a new Radar part. The radar is pretty nice for the 1st half of the game.

Another hidden part:-  On the snow mission where you have to destroy the crates, go in the crack to the right of the starting position and destroy part of the airplane to reveal a little cave that has an optional part for making left arm weapons or shields power up.

Create overweight AC's:-  After beating the mission mode the first time in Armored core 2, you can create overweight AC's! This means you can use your AC, even though it is overweight. You must get the end-of-game credits for this to become active.

Human plus enhancements:-  The human plus enhancements from the first Armored Core games have returned. Only better. First off, you have to get below -50,000 credits. You will then see a cut-scene showing your character getting implanted with stuff. Here are the enhancements you receive each time you get below -50,000 credits. NOTE : You must not beat the 1st mission (after the Raven Test) or these options will be unavailable. You have to loose 50,000 credits for each enhancement. On the plus side, any changes to your AC will carry over, but you will have to input your name again.

1st time : Improved radar:-  This makes most radar units obsolete! It gives grid radar with a decent range and enemy info.

2nd time : Long-Range Blade:-  This enhancement allows you to shoot projectiles from your energy blade. Press Circle to slash, then quickly press X for the shot.

3rd time : Enhanced Cooling:-  Your AC unit will cool twice as fast as normal.
4th time : Improved Mobility:-  This allows you to fire heavy back weapons while moving, instead of standing in place.
5th time : Improved Boost:-  It halves the drain on energy from the booster, allowing you to boost twice as long.

Fixed camera view:-  Hold Circle + X + Start while playing the game. The game will pause. Resume the game with the view fixed.

First person view:-  Hold Triangle + Square + Start while playing the game. The game will pause. Resume the game with the new view.

Return to default view:-  Pause the game, then press Start.

Fixed camera view (Japanese version):-  Hold Circle + X + Select while playing the game. The game will pause. Resume the game with the view fixed.

First person view (Japanese version):-  Hold Triangle + Square + Select while playing the game. The game will pause. Resume the game with the new view.

Return to default view (Japanese version):-  Pause the game, then press Select.

Gameshark Codes

(M) Must Be On EC87A2E81456E60A 
All Missions Completed 3CAE102C1456E7A6  1CAE10F81654E5A7  1CAE10FC1654E5A7  1CAE10001654E5A7
1CAE10041654E5A7  1CAE10081654E5A7  1CAE100C1654E5A7  1CAE10101654E5A7  1CAE10141654E5A7
1CAE10181654E5A7  1CAE101C1654E5A7