Being basic infantry, the Forgotten is an anti-infantry unit. It can be destroyed by anything with a machine gun, or by basic Riflemen/Militants on your team.
The Missile Squad is the Forgotten anti-air unit. While they are capable of damaging your vehicles (and you should be wary of this), their main target is your air units, and they will actively reposition themselves to attack.
The Rocket Fist seems to be just as common as the regular Forgotten infantry unit, and it unfortunately is one of the most annoying enemies you will encounter. This infantry is a decently armoured anti-vehicle unit that will tear apart even the toughest tanks pretty quickly.
More than just a pretty face, the Forgotten Sniper Team, like their GDI counterpart, excels in quickly taking out infantry from afar.
This is an anti-infantry vehicle with limited range. It should be an easy target for any of your vehicles.
This is a heavy anti-tank vehicle capable of thrashing some of your toughest tanks. Send in some heavy vehicles of your own to destroy it.
The Scrapbus is an anti-air vehicle capable of only attacking air units. It is incapable of attacking anything on the ground, thus it is easy to destroy, as long as you’re not using any planes.
The Forgotten managed to capture some GDI Mammoth Tanks and modify them for their own needs. What isn’t modified is their role of a heavy anti-armour vehicle.
Machine Gun (MG) Nest
The Machine Gun Nest is an infantry-operated machine gun capable of mowing down your advancing troops, unless you use a long range sniper or machine gun vehicle to destroy it first.
This is a heavy turret that specializes against aircraft. Be careful if you plan on sending in your air units, and consider sending in a group of strong vehicles first.
This is a very powerful anti-vehicular artillery launcher. It has a minimum range, but good luck getting close to it without a strong offense, as it is liable to destroy your vehicles in their tracks.
Complementing the Demolisher Artillery, the Reaper Artillery is instead an anti-infantry version, capable of devastating your foot soldiers very quickly at long range.
Surface-to-Air Missile (SAM) Site
As expected, the SAM site is a missile launcher capable of taking down even the strongest air unit. Kodiaks and Salamanders beware, this is not your average pee shooter. The SAM site is a strong opponent to every air unit.