Crap, there's something oddly arousing about this scenario. The scary thing is that there are actual official Pokemon with settings this dark lol. None of them are sexual of course. They would instead invole the brutal murder and torture of the victims. Just read what Palossand does to other sentient Pokemon and potentially humans.
Funnily enough, what I'm curious about is if this lewd Cofagrigas actually does have a master-type figure? It could be another pokemon, or it could be totally delusional, or the master has long dead and all victims are just out of luck. Then there's the other possibilities lol. If this Pokemon can actually extend a person's life and keep them in a fresh state instead of actually turning them into mummies, there could be a dystopian society where this Pokemon is used as a type of cryopod lol. Now that's an unconventional way to bypass the sleeper/generation ship technology issues.
They always cut stuff like this off when it gets to the best part. How about showing some time passage and how it affects her? Anything than just writing down in a small text box about what happened next. Show, don't tell.