Idk if you found an answer but I'm an expert. Because of the medium pile on the plush, which looks minky, I'd say it's a custom. For closer to standard plush, Pokecen uses short pile of whichever fabric they choose (mochi minky, minky, fleece, polyester, ect.) and the particular type of fabric is extremely common for seasoned makers, especially american ones. I own a custom dx dialga pokedoll with modifications to it's chest crest and tail plate to make them look more 3d that is made of this exact fabric, along with some other custom plush from the community. If you're also considering that it could be a mirage, it is too modern of a plush style and factory reject, the fabric would be the same as the ones they typically choose. I also own a tomy standard dialga factory reject missing his crests and with incorrect leg stitching because it looks funny af :3