Pros Can make 2-5x as many workers/units
Cons Weak units. Detection expensive. Less reliable aoe damage.
Zerg Units and structures
Larvae
Overseer Detector and dropship
Major (special drone) tankier worker that cant fight or build
Queen Defensive healer. attack while move. Can boost broodmother
Broodmother pivital economic and production unit. Produces larvae. 1 for every 2 hatcheries advised.
Ling very high dps x3 units with high speed and low hp
Baneling difficult to use well. fragile aoe castor. kamakazi
Roach solid bruiser unit. bonus vs mech. can selfheal and burrow
Hydra backbone of zerg. High dps.
Mutalisk flimsy flippy flappin harrassment flyer. exspensive
Drake strain mutalisk
Swarmhost locusts excell vs buildings
Infestor aoe
Ultralisk
too
AA options
Broodmother
Burrow
Swarm hosts are siege units meant to kill castle. Also effective to support your army in fights especially vs beast.