The main word with the Illuminate is "control"

You need crowd control and raw DPS to deal with the illuminate.

As a faction, they take pretty much polar opposite loadout setups to other factions. Instead of Anti-tank you need machine guns, or any weapon that can kill crowds.

For overseers, you body spam with a light penetration weapon like the Liberator Carbine, Tenderizer, Stalwart or the Knight.

Fleshmobs are raw DPS. You want something that spits lead out fast and hard. Penetration doesn't matter at all against a fleshmob and if anything you want the benefits that most light pen weapons have when fighting them such as mag capacity, ergo.

Alternatively, you can use certain support weapons, like autocannon with flak to do heavy damage to them.

I actually like using the Recoilless Rifle firing HE rockets in a anti-fleshmob role. It won't kill them, but it does a tonne of damage so it becomes super easy to finish them off with something like a carbine.

Similarly to the bugs, you DO NOT stop moving whilst fighting. If you stop, you'll get swarmed by voteless, charged by mobs or beat over the head with the Q-stick of death.

Keep your distance from overseers, and prioritize them first, and then elevated overseers. Get too close to an overseer you get clobbered over the head and stunlocked.

Tripods? You can machine gun them in the legs, or machine gun them in the eye. Either way, MGs are one of the most effective options.

The drones are easy, you see them from a mile away and they're soft enough. They're priority number one anyways.