The "Pokémon Essentials" fan-made toolset for RPG Maker has been around for 11 years now, but it seems Nintendo has had enough of it. Nintendo has sent out a takedown request/copyright notice about the toolset, asking PokéCommunity to remove all download links to the toolset, as well as the upload itself.
Pokemon Essentials was a fan-made toolset that allowed RPG Maker users to create Pokemon-theme games. It used assets ripped straight from various Pokemon games, and was even used to create Pokemon Uranium, a Pokemon fan-game that saw release in 2016. Nintendo also swooped in and took that game down.