Geth Trooper

Geth Troopers are the standard ground forces of the geth throughout the Mass Effect series. On the battlefield, they usually attack in groups or are supported by stronger geth units.

Mass Effect
Geth Troopers are standard geth infantry. These units are lightly equipped, with no exotic weapons, and are normally found in groups of two or more. They are dark gray in color, with pale green synthetic "flesh" and a bright blue 'flashlight eye'. They lack heavy armor, resulting in a weakness to weapons fire, and their light weight means they are vulnerable to biotics or grenades.

Tactics
These enemies possess neither the firepower of the Juggernauts nor the mobility of the Hoppers, but are versatile foes nonetheless. They are encountered in a wide variety of combat arenas, so caution must be taken to account for the many differing settings where they may be fought.
 * Tech Talents such as Sabotage or Overload to lower their shields or overheat their weapons will make them vulnerable targets.
 * Utilizing Armor Piercing Rounds will increase your damage against these foes.
 * Biotic powers such as Lift and Singularity will lift geth into the air, making them incapable of combat and easy targets.

Mass Effect 2
In Mass Effect 2, Geth Troopers are the most common type of geth encountered. They differ in color from previous encounters, being white instead of steel gray, thus bearing more resemblance to Geth Shock Troopers from the previous game.

Capabilities
Offensive

They are equipped with the standard Geth Pulse Rifle.

Defensive

They have the Geth Shield Boost ability, which can strengthen their shields or replenish them when depleted.

Tactics

 * Disruptor Ammo, Overload, Shield Penetration Upgrades and weapons which deal good shield damage already are the best methods of dealing with their shielding.
 * Shockwave will also briefly stun enemies when it impacts their shields and inflict light shield damage based on its impact force.
 * Explosive Combat Drone can serve as a distraction and will cause additional damage if destroyed.
 * These units should be close to the bottom of the priority list when it comes to AI Hacking. At best they will be a short distraction. There are usually always targets more suitable to hacking around when encountering geth, since the Troopers are often supported by at least one heavier kind of geth unit.
 * The Arc Projector can wreak havoc on entire squads of troopers. It is best used at choke points.
 * Geth Troopers tend to be quite weak, but usually come in significant numbers. They are also usually supported by more powerful units, such as Geth Hunters.

Mass Effect 3
Geth Troopers return as enemies in Mass Effect 3. They are once again colored steel gray with green "skin", now with white armor markings.

Capabilities
Offensive Geth Troopers are armed with a Geth Pulse Rifle and can melee attack anyone who gets too close to them. They can also execute downed players.

Defensive Geth Troopers have no shields or armor, but can evade attacks by making a jump to the side.

Tactics

 * Most sniper rifles can immediately kill Geth Troopers with a headshot.
 * Geth Troopers can easily swarm reckless players. Other geth units will often try to flush the player from cover, allowing Troopers an opportunity to cut them down with their rapid-firing Geth Pulse Rifles.
 * Because they are both weaker enemies than most and capable of inflicting moderate to severe damage in numbers, Geth Troopers also act as distractions to give more powerful geth units a chance to close in. When focusing on a group of Troopers, watch out for cloaked Geth Hunters and Geth Pyros either moving with the group or approaching from other directions.
 * Weapons that deal area of effect damage, or powers that deal with them outright are very useful here. An Overload focused on damage can sometimes deal with Troopers in just one go. Energy drain is not as effective for killing a single trooper, but is certainly very effective against clusters of enemies, when the rank 4 evolution "Radius" is acquired. A single energy drain can not only weaken Geth significantly, but also (with the right upgrades) provide full restoration of shields, and/or even a 40% boost to damage protection for 10 seconds. Finally, Grenades are very effective at eliminating clusters of troopers, especially the Cluster Grenades as they split up and can cause massive damage over a very wide area.
 * If, in Multiplayer, your team is occupying an area (for example, for some of the objectives) on earlier waves and there are not enough of you to cover all approaches, it can be very useful to lay Proximity Mines on one area - when evolved correctly, they can eliminate whole squads of the Troopers you were worried might flank you.
 * They are less likely to dodge attacks: if staggered by gunfire, if you are in close proximity, or if they are focused on another target.