Okay. I promised. Let's fucking get this train back on track.
Grimer: I honestly like slimes, but Grimer is pretty low tier in that category. His shape is just unpleasant. He puts me more in mind of a dude melting than a sentient pule of sludge. The weirdly distinguished hands are part of it, as is the very distinct head area shape thing. 2/5 is probably harsh, but whatever. I'm back and I'm gonna rock this shit.
Muk: This is more what I want out of my toxic slime monsters. This thing looks like a heap of creeping sludge that is gonna ruin your day. Also, did I complain about the overuse of purple in Gen 1 Pokemon? Because Grimer and Muk contribute to it. Still, Purple is a decent toxic sludge color. 4/5.
Shellder: Shellder is adorable. Lookit those big eyes and that derp tongue. The shell's lines and spikes are nice, and the black, indistinct body is fine for a shellfish. 4/5
Cloyster: Vagina jokes. We good here? I actually love Cloyster's shell (it's awesome, that's what an angry, aggressive death clam looks like), but the super distinct orb body and spike on Cloyster don't do it for me. I'd like this design more if if it had a less distinct shape like Shellder, I think I'd like it more. I get it's the whole pearl thing, but I just don't like it. Still, that shell is awesome. 3/5
Gastly: Literally all purple pokemon today. Still, he's cool. Orb design works way better here, though I'm still not the biggest fan. Ghostly trail is wonderfully jagged and cool. Fangs are sorta odd but actuall work to me and the eyes are appropriately menacing. The eyes actually coming off the body is actually a great, great touch and really hammers home that he's abnormal. 4/5
Haunter: Mixed opinions, here. I don't like the shape of Haunter's main body, but the mouth and the eyes are also pretty awesome and I absolutely adore the disconnected hands. Too sleepy to decide on 3 or 4, so credit for the disembodied hands. 4/5.
Gengar: You know what kind of ghosts are awesome? Not fat ones with stubby legs and arms, that's for sure. Holy crap, I hate all the trade evo pokemon almost. Face is great, but the rest of it enrages my sleepy mind. 2/5
Onix: Something not at all purple. Not a ton to stay here. It's a giant rock snake made of boulders. Rocks are nicely craggy and detailed. Feel a bit weird about the horn, but eh. It's a solid design 4/5