I wonder if the Meathook's hooks will have some sprites similar to the Doom Alpha rifle bayonet blades, just to fit the art style.
Since the Marauder has a dog, maybe there's a fourth canine foe to fall under the dog collar.
Don't see the point of the Prowler but he has a triple projectile shot, which sort of "canonized" the Malwrath's triple shot i guess.
Doesn't the Carcass have a similar attack to the Whiplash and Tyrant that involves an almost homing-like floor shockwave attack?
Maybe that could be turned into something that eventually turns into the energy wall shield, for the sake of visual feedback.
His other attack is a burst of ring shaped projectiles, so i can see him fit as a variant for the Arachnotron slot.