For the first half of the story, you'll spend most of your time fighting with drug dealers and other thugs. They mostly stick to using guns and the occasional grenade. They don't vary much.
These guys all wear track suits so you just know they're douchebags. They're the weakest enemies you'll encounter with regular fire arms and sniper rifle, with no special abilities or traits.
These pretty much just replace the Akurans at some point and are more-or-less the same thing. They can throw smoke grenades that will make you cough and be unable to attack. Dash away from the smoke if they hit you.
About half way through the game, the DUP will come to town and you'll have to fight a lot of them. DUP enemies have weak (or not-so-weak) concrete powers they got from Augustine, so they have more abilities than the criminals from earlier.
The most basic type of DUP enemy isn't very remarkable. It will fire at you with its assault rifle or hit you with short-ranged blasts of concrete. If they can't see you, they might throw a concrete grenade at you.
An advanced version of the Pawn. It has all of the Pawns weapons, plus rocket launchers and gas cans that work as molotov cocktails. They can create concrete barriers to hide behind. These barriers can be destroyed with enough force.
Knights use tear gas grenades to stun you. You won't be able to attack if one hits you, but you can very easily dash away from the gas to immediately regain your composure. Delsin can absorb the gas for smoke powers. These guys can launch themselves into the air to follow you to high places or escape dangerous situations. They have their own version of the Comet Drop they can do after launching themselves. They can launch themselves to walls and create concrete platforms to stand on and shoot you from. Knights are more armoured than Pawns.
Bishops can summon a concrete barrier, either around themselves or their allies. Take out their barriers with homing missiles. They move quickly along the ground and can avoid your attacks this way. They can encase your legs in concrete from a distance. If you see concrete circle around and close in on you, that's what's about to happen. You can escape by dashing, either before or after you're trapped.
These brutes are covered in concrete armour. They move slowly but barely react to your regular attacks and have massive miniguns that will completely obliterate you if you're not careful. If you get close, they'll smash you with their weapon. They take a lot of damage and if you whittle their health down and don't finish them quickly enough, they'll encase themselves in concrete pods and regenerate. If you get behind the pod, you can finish them off before they can regenerate.
Super Rooks are too tough for puny miniguns. They're much more mobile than Rooks, being able to leap huge distances and slam into the ground. They don't use weapons at all, instead relying entirely on concrete abilities. They'll attack with both short and long ranged concrete attacks. These are certainly the most fearsome DUP enemy.
There's only really a few of these in this game, during story missions. They're not too tough to take out, as long as you avoid their rockets. One or two quick flurries of neon bolts will be enough. Or a Singularity. They actually go down faster than Rooks.
These only appear at Curdun Cay. Holographic demons and evil things that are generally more powerful than even the DUP agents. There's a lot of variation among Demon enemies.
These angels fly around and fire powerful lasers. The lasers are continuous and can be a real pain if you don't know they're coming, but Fallen Angels themselves go down with very little effort. It's usually a good idea to take them out first. You can defeat an entire group of them with one good blast of homing missiles. You can't do anything but run while you're being hit with their lasers so don't try to take them out while you're under fire.
Night Terrors are similar to Fallen Angels, with red bat wings. They attack with fire balls instead of lasers and go down just as easily.
These things attack by summoning Swarmers or throwing skulls. They float around and take a lot of damage to go down, but they do have weak points. Target the orbs that surround them to take them out like any regular enemy. These orbs are constantly moving, making them difficult to hit.
Wraiths don't have any projectiles, but your neon bolts bounce right off of them normally. They walk slowly but can dash at you if you get too far from them. Their melee attacks are very powerful. Use Stasis Blast (followed by melee attacks or neon bolts) or a finisher to take them out. Melee them if you have to, but retreat when they're about to swing at you. Homing missiles work.
These little things are summoned by Summoners. They crawl along the ground and have very little health. There's strength in numbers, though. Red ones get close and explode. (You'll be able to see the range of their explosion as a ring around them.) Blue ones attach themselves to you and damge you. Use a stasis blast if this happens. You can take out large groups of them with stasis blasts, or attack them with melee attacks to smoosh them one or two at a time and refill your finishers.
These are the only things you'll fight in the arena that aren't holograms. They might do you more good than harm if you take advantage of them.
These only appear in Beta Survival and one specific story mission. They're stationary and will automatically target you, but if you can get behind them, you can overload them and cause them to target your enemies instead. It's basically always better to overload a turret than destroy it. It can protect you for a while if you stick around, but it will eventually explode and damage you if you're standing too close. Only one turret will appear at a time, so either destroy or enslave it to get rid of it and have another one appear elsewhere. Turrets show up as turret-shaped red icons on your minimap.
Flying Auto Turret
These don't hurt too much, and play more of a role as carriers of power ups than as enemies. They only appear in Survival, and each one carries one of four different coloured shards that will have different effects if you destroy the turret and absorb them. Blue will make your regular bolt more powerful, Yellow will double your multiplier, Purple will make you invulnerable, and Green will give you unlimited finishing moves. Of course, all effects are temporary. Two flying auto turrets can be in the field at a time, whether you damage them or not. If you leave them lying around, they'll stay there until you absorb them and no other turret with come to take its place. Flying auto turrets appear as white circles on your minimap, and the shards they drop appear as coloured diamonds.