Drowzee is just awful and not viable. I can't think of much it could do besides be a decent insomnia switch into foongus and an undesirable spreader of para. CM and wish would be a waste of time.
It's outclassed by pokes that aren't even very strong/common in the meta currently, but, even if they didn't exist, drowzee has very little going for it. Personally, I'd expect phanpy to be D rank, but sadly it exists in a meta with onix, sandshrew, and drilbur.
However, phanpy is cute as f*** so it deserves honorary D rank imo even though it's so outclassed. Drowzee is ugly and creepy.
It's so f***ing cute omg.