The normal zerg roach is a lower tier unit that is often in crowds of it's brothers and has a moderate amount of health and a close range acid spit attack that does low damage. Nothing too dangerous although it comes in two slightly more dangerous flavours as well as having a few other interest points like the mass of hidden roaches that spawn in when you conquer roach hill in the middle east of the map.
The roach does have a primal variant that is most frequently seen as a pod drop.
Base Strain Edit
a.k.a Normal Roach Edit
The base strain is pretty easy to take on with the only threat being the numbers of which they appear in with the early swarms being around 4 to 8 but they quickly spiral out of control as the game progresses until they fill out massive hordes among other units.
Corpser Strain Edit
a.k.a Other Roach Edit
You'd expect this roach strain to be a great pusher with it's ability to create tiny clones from the corpses of your many troops but in CP2 they have been neutered somewhat with this ability taken away. They really are only slightly more dangerous version of the base strain with a slightly larger hitbox so they can block movement a little easier. They get thrown into the hordes commonly as the game goes on so keep in mind their higher hitpoints and damage.
Vile Strain Edit
a.k.a Sticky RoachEdit
The most dangerous type of roach, but fortunately also the most rare. This roach is very slightly tougher than the normal strain but has a slowing spit that debuffs any unit hit by it's basic attacks both in attack speed and movement by 50%. This can set you up for a more damaging enemy and lead to a quick almost unavoidable death. The only way to stay safe against them is to stay behind allied units or fight them when you can isolate them and take them down without interruption. In short treat them with respect and leave room in your offensive plans in case they turn up with a horde of allies.