This request is from "brianpokemon" of DeviantArt, and it's a mermaid version of another Pokémon character: Bonnie from their XY series.
While doing an image search for her, I noticed she has her own Pokémon she calls "Squishy". I kind of abandoned the whole franchise after Season 4 or 5, so I'm not up on these new little critters. Still, I hope you like this as much as he does.

Characters belong to Nintendo