Roles:

Nyx = Rifler and IGL.
They are the frag machines, able to win duels, spray across maps, get single taps, one after another and generally dominate the gun play in a game.

cLose = Main awper and support player.
The support player holds everything together and keeps things rolling, by using fantastic game sense and positioning. They stay alive as long as possible and provide vital information for their team. A good AWPer will not simply hold the same angle or spot 24/7, but will remain mobile within each round and throughout the entire game, seeking to catch people unaware.

Zin = Lurker and rifler.
A lurker will do exactly as the name suggests, they like to take things into their own hands, moving about the map and keeping the enemy on their toes. With perfect game sense and positioning they are able to flank opponents and get surprise kills.

Goku = Entry fragger and support player, also strat caller.
The entry fragger will usually rely on excellent raw aim and fantastic recoil control, doing exactly what it says on the tin and getting the opening kill in a round.

Cioma = Rifler and secondary awper.
Being a solid rifler is never a bad thing, nobody on your team is going to moan at you for only using a rifle every round as they might if you only used an AWP for example.