Raiders/Scavengers/Roekaar/Outcasts/Exiles/etc.: Humanoid grunts are pretty much all the same- while their rifles can be deadly if you let yourself get caught in the open, the gunslingers themselves are easy game for your endless arsenal of techs, biotics, and bullets. They’re also especially vulnerable to exploding canisters
Sharpshooters: No matter what species or planet they hail from, you’ll know these enemies by the visible-laser-beam sight they all use. As ever, don’t let the laser linger on you- all sharpshooter rounds pack an outsized punch.
Anarchists: Evil (presumably) turians in tech armor. Like all entirely armored creatures, fire is a good remedy.
Pariahs: Evil (it would seem) asari. Their biotic field bounces your own biotic attacks right back at you, so watch your targeting. Nothing like seeing your own Singularity come barreling back toward you.
Agent: Evil (if you can believe it) salarians. Their key tactic is to create holographic doubles of them-selves, though the image always has a telltale shimmer.
Saboteur: Evil (from a certain point of view) angarans. They can use their biolelectrics to take out your shields with one pulse, so prioritize them as targets.
Berserkers: Evil (if you care to make that distinction) krogan with charging and flak cannon attacks.
Hydra: The giant robot of this particular game is pretty unremarkable- aim for the optics and get out of the way when its aiming beams align. Also, of course, be aware that these can take a lot more damage than the average enemy. Unlike other giant enemies, Hydras seems to have real trouble connecting with close range attacks.