A few minutes ago I saw an episode of The Cosby Show where Cliff is building a haunted house and borrows a drill from his neighbor and when I saw it I didn't know that The Cosby Show even had a Halloween themed episode so it was new to me. Did they have other Halloween themed episodes of The Cosby Show every season?
Bestie

There was, yes.

There was a couple of Halloween-themed episodes: season 2, episode 6, titled "Halloween". This is the episode where Vanessa first starts dating Robert. Season 4, episode 4, "Cliff's Mistake" also has a Halloween plot. If there were others, I don't know of them.