Question: slytherins who fought in the battle of hogwarts?
Answer: Most of Slytherin fought alongside Voldemort. Slughorn fought on the Hogwarts side. Draco Malfoy, after ambushing Harry in the room of requirement, seems not to really have fought; it seems his parents were more or less with Voldemort but didn't actually fight. I think we all know about Snape.