He probably wouldn’t be very good, since his expertise is in potions and not defense, and he would have had to leave after a year for some tragic reason.

@Icecreamdif I thought Slughorn as a Dark Arts teacher would've fit well with him being likeable to Harry and other Hogwarts students after last one being super dreadful.

But then the story would have needed to end with something happening to Slughorn for him to leave. Snape already needed to leave at the end of the story, and he had spent the whole series wanting to be DADA teacher, so it made sense.

Besides, I think it works having Lupin as the only likable DADA teacher.

Should I be depressed that I have no idea who you’re talking about

Have you read or watched Half Blood Prince yet? If not, it is perfectly understandable that you don’t know who Slughorn is.

I’ve watched and read all the Harry Potter stuff I just don’t pay attention to side characters lol—

He is the potions master in half blood prince

he would most likely be extremely bad (akin to lockhart) and would instead use the classes solely to add people to the Slug Club. He would most likely leave the school after Katie Bell's affliction with the cursed necklace

@Kirishma.213 Is it just the name you don't recognize or you don't remember him at all (he was this potions master in HBP if that helps)