Ghost Recon Cheat Codes for Gamecube

Easy mission completion:
Use the following trick to complete Missions without doing the objectives. Play the mission like firefight mode. Once you kill everybody, the mission is automatically complete with all objectives done.
Submitted by: Zach

Medals:
Purple Heart: Get wounded or killed in action.
Bronze Star: Get 15 kills
Silver Star: Get 20 kills
Distinguished Service Cross: Get 25 kills
Congressional Medal Of Honor: Get 30 kills

All heroes:
Successfully complete the first twelve missions in campaign mode to unlock all twelve heroes as playable characters in quick mission and campaign modes. They include Henry Ramirez, Nigel Tunney, Will Jacobs, Jack Stone, Guram Osadze, Susan Grey, Klaus Henkel, Buzz Gordon, Lindy Cohen, Astra Galinksy, Scott Ibrahim, and Dieter Munz.
Submitted by: Zach

Enemy calls for backup
Usually when you kill every enemy except for one, he will either shoot his gun straight up, or shoot a wall. If you wait about two minutes, about three or four more people will appear. When they shoot the wall or straight up into the sky, they are actually calling for backup. When another soldier far away hears a gun firing, they will run towards it to aid their friends. If you find a group of people and they all are killed except for one, and he begins to sprint away, it is imperative that you catch and eliminate him immediately before it is too late.

Black Needle: Easier completion
Leave Bravo at the insertion/extraction point. Take Alpha and secure the crossroads and rescue the soldiers in the buildings. Make sure you only have one soldier remaining (kill the other two if needed). Go back down the road where about five soldiers are waiting. Let them kill you. If done correctly you should have a mission complete.
Submitted by: Zach

Recommended weapon
In multi-player mode, choose a rifleman and get Kit 6 (MP5 SD, extra ammunition). This kit will almost win every battle because it has a 30 shot clip and you can walk while looking in the scope. You will have great accuracy with most of the shots. It really does not matter what gun your opponent chooses, unless they select the same kit. The M136 and other powerful weapons take a long time to aim.

Hidden weapon
In the multi-player level in the city, go to the second floor of the bank. Behind either of the doors, facing out of the window will be a 50. cal.

Fever Claw: Sniping location
When playing in multi-player mode, find the large building with a Russian flag flying in front of it. Go through the gate and take a right, then a left, then another left, then turn around. There will be a stairway. Go up it into the building and go up those stairs. Take the first left and you will find a very nice sniping location.

Zebra Straw: Other threats besides artillery
When you meet up with the allied tank go forward. The first building on the left will have several soldiers in it. One man has an anti-tank rocket. Eliminate him as soon has possible to stop him from destroying the allied tank.