Banette if it hasn't already been done?
Banette’s a premium spookster, and in terms of overall vibes, actually one of the most unsettling. Those oddly jagged eyelids, zipper mouth, and limp, hanging hands just collectively feel wonderfully OFF, y’know? As a Ghost-type, one may expect it to be somewhat off-putting, but the typical Ghost-type often just has chaotic-and-mischievous vibes. But there’s something about Banette that seems…..resentful.
For good reason! Banette’s concept is that it was once a doll who was abandoned by its owner, and has since come to life, possessed by sheer spite to locate the child who disowned it, so it can “exact its revenge”. A pokemon that canonically wants to harm a child is pretty chilling, and it’s played pretty seriously in a way few other pokemon are.
Basis-wise, it pulls from the relatively common concept of haunted dolls – dolls said to be cursed or possessed in some way. It derives from voodoo dolls as well,  being stated to stick pins into itself in its dex entries and being strongly associated with the move Curse, which appropriately tends to have an animation of a pin being stuck into the attacking pokemon. It also has parallels with the concept of Japanese tsukumogami, inanimate objects that come to life after 100 years and may harbour negative feelings if poorly-treated, though they’re generally associated with practical items like furniture and tools. It’s also worth noting that despite its name and status as the Marionette Pokemon, Banette (unfortunately) derives very little from marionettes, other than perhaps the hanging posture of its arms. Didn’t stop the anime from referencing them though!
Banette’s spiteful energy is also said to be held back by the zipper on its mouth, so you’ll never guess what happens when it Mega Evolves! Spilling out of its body as bright purple legs and claws, it adds a pleasant splash of colour to the design, though I feel its efforts to appear more intimidating ultimately undermine its general eeriness. Sure, it’s got claws now, but it’s hard to take all those superfluous zippers seriously. Did this doll belong to Tetsuya Nomura or something????
Shiny’s a pretty subdued cerulean colour, which is less creepy than the dour grey but shinies are SUPPOSED to be pretty so I’ll accept it. Looks really good with the eyes and zipper, too.
Overall, Banette’s a great pokemon, and incredibly unsettling both in terms of appearance and backstory. That said, I wish it did a bit more to evoke its dollishness – things like stiches, patches, and loose threads may have complicated the design a bit, but they would make it much more immediately recogniseable as a child’s toy rather than just a grey zipper-mouthed imp thing. Good nonetheless.
Now make an actual marionette/10.
