In the After Colony timeline there are generally few explanations about the technology, as the series focuses more on character development. Most technology is assumed to work in at least similar fashion to the mobile weapon technology from Gundam's Universal Century.
Mobile Suit Technology - Offensive Weaponry
Beam Type Weapons
Beam type weapons are weapons used by Mobile Suits that generated either a blade or a bullet-like projectile by charging the particles in the atmosphere within a given radius and focusing it via the convergence ring (beam rifle) or the beam formation unit (bladed beam weapon).
Beam weapons are the most advanced weapons used by Mobile Suits. While beam weapons can be built for ordinary MS, they are especially powerful when made using Gundanium alloy. The complex alloy allows the charged particles to reach heat temperatures which would incinerate ordinary materials. For example, the Buster Rifle, which Wing Gundam carries, charges all particles in a 150 meter radius, creating a maelstrom of hot plasma. The gun's convergence ring concentrates the energy into a single devastating beam capable of destroying a battleship in a single blast.
Close-combat beam weapons use the same principle as long range beam weapons, only instead of projecting beams of charged energy, they contain the beam in a continuous arc, even underwater. The ionization field surrounding the beam causes any matter it hits to become super-charged, effectively ripping it apart.
Defense Against Beam Type Weapons
There is no armor capable of defending against beam weapons. The Gundanium alloy used in the Gundams' armor and the Planet Defensors of the Mercurius and Virgos is highly heat-resistant and virtually immune to corrosion, but it's still not immune to beam attacks. It does, however, create an "anti-field" that repels beam attacks to some degree, reducing the damage delivered, but not stopping it outright.
The best way to stop beam attacks is to avoid them entirely. Many Mobile Suits have been designed to have higher-than-average mobility and evasive capabilities. A notable example is the Gundam Deathscythe Hell. Its Active Cloak can confuse visual sensors and the Hyper Jammers can block other readings, making it invisible to radar. The cloak also helps to disperse the charged particles of beam attacks.
Beam Vs. Beam
When two beam weapons collide in melee combat, the charged particles repel each other, acting as if they were solid. The size, power and speed of the Mobile Suit becomes the deciding factor in such combat, just like with two humans dueling with swords.
Types of Beam Weapons
These were the most powerful of the beam type weapons. When the trigger is pulled, energy from the energy unit is passed into the beam generator then filtered into the pressure ring. The convergence ring would then focus the charge energy into a beam, which would then be forced out of the muzzle by the acceleration ring.
This type of beam weapon includes beam cannons, beam rifles and the OZ space cannon.
These were utilized for close combat between Mobile Suits. When activated, energy would be supplied by the beam supplier. The acceleration ring would push the energy into the energy condenser from where it would move to the beam generating unit. The energy would then move into the beam formation unit where it would be focused into a continuous arc of energy.
A unique compound which can only be produced in the zero-gravity conditions of space. In addition to its incredible strength--several times the strength and heat-resistance of titanium, Gundanium alloy is electrically non-conductive and cannot be detected by radar. However, this material is expensive and difficult to manufacture, making it unfeasible for mass production. Gundanium is created through the most advanced refining, fusing, and deoxidizing techniques, which are only possible in space. The complex formula was first called GND, short for Genetic on Universal Neutrally Different Alloy. Later the suffix "-nium" was added to distinguish that alloy from other similar alloys that were being developed on Earth. Gundanium was still superior to the competition because of its zero-G creative process.
A stealth device used by the Gundam Deathscythe. The hyper jammer emits mysterious particles that scramble enemy cameras, making the Gundam invisible to visual sensors as well as radar.
Mobile Doll system
Developed by OZ's Colonel Tubarov, a loyal supporter of the Romefeller Foundation at OZ's Lunar Base, the Mobile Doll System uses a powerful computer system equipped in a mobile suit that allows it to act on its own without a human pilot. Through this method not only would it help prevent Romefeller from sacrificing the lives of their pilots, but it also would prevent them from using poorly skilled pilots in battle.
The "planet defensors" are small disk-like drones that can be separated from mobile suits and can arrange themselves to deploy an electromagnetic forcefield that would protect the mobile suit. The OZ-13MSX2 Mercurius mobile suit was developed as a testbed for the planetary defensor system by OZ. The Mercurius' forcefield was so strong that it was even able to block a shot from Wing Zero's buster rifle although a subsequent shot could penetrate the weakened shield. The defensors were carried over into the OZ-02MD Virgo mobile doll (though it appeared less powerful then one used by the Mercurius), which combined features of the Mercurius with some from its offense-focused counterpart, the Vayeate. A Virgo on its own can only generate a shield that protects from fire in one direction (as one Virgo only carries four defensors) - however, three Virgos working in concert can deploy their defensors in a globular shield, as can the Mercurius (which carries ten defensors.) OZ later developed an advanced variant of the Virgo, the WF-02MD Virgo II, which carried eight defensors per unit; this machine was stolen by the rebel group White Fang and is often associated with them.
Capable of defending against both projectile weapons and particle beam weapons, older laser weaponry was deployed that could penetrate the field. However, the reason the lasers were no longer in use was due to extremely rapid overheating in combat, often leading to the weapon exploding in the Mobile Suit's hands. Planet defensor fields were also breached by melee attacks, suggesting that it takes a certain amount of force (either constant like a weapon attack or focused like a laser) to break through the field.
A special system used on G-UNIT mobile suits such as Geminass 01 and 02. The PX System acts like a G Gundam Hyper Mode by doing a number of things such as relaying battle data to the pilot through a flip-on helmet when activated. The suit also changes to reflect the change in the pilot to yield better performance in combat. However there are several drawbacks, one of which being that the system can only run for 90 seconds. If this is exceeded there are serious consequences for both the pilot and the mobile suit as the PX System stretches both to their respective mental and physical limits, and in extreme cases it can even kill the user. Another noteworthy feature is that the PX System has two modes: normal and overdrive. Overdrive brings the system to the limits of its power, though only the pilot can turn off the system as it overrides all failsafes. Thus this allows it to last longer than 90 seconds but at great risk to the pilot's life.
The ZERO (Zoning & Emotional Range Omitted) System is a technology for interfacing the brain of the pilot with the mobile suit's computer (comparable to the Universal Century's biocomputer in the F91 Gundam). Only two known mobile suits were ever equipped with this system, the XXXG-00W0 Wing Gundam Zero and the OZ-13MS Gundam Epyon. The ZERO system decreases the pilot's reaction times as there is no need for traditional visual interfaces.
Zero System 2.0
This modified system provided better and more detailed information than the systems in either Wing Zero or its rival, the OZ-13MS Gundam Epyon. However, these improvements came with a price; just as the benefits were strengthened, so were the flaws. While the original Zero System merely urged its pilot to follow certain courses of action, Version 2.0 actually forced them to follow these paths.
Zero System 2.5
This system provided much better technical data and information, but had the drawback of taking control of the mobile suit sometimes when activated. It should be noted, however, that Zero 2.5 lacked the mental effects which its predecessors possessed.
Gundam Official - contains technologies.