People call it an Xbox exclusive, because it is. But Epic is obviously not a studio of microsoft. However, I'm fairly certain that Microsoft pays the team for console exclusivity and even probably determines release dates and advertisement.
Nintendo ONLY does spin offs. They don't make the versions!!
Nintendo doesn't even do spin-offs.
Nintendo co-own the franchise with GameFreak and Creatures Inc. Nintendo have some ownership of GameFreak and own all of Creatures Inc. Nintendo is also the sole owner of The Pokémon Company.
Spin-offs are all handled externally. PokéPark & Ranger games by Creatures Inc., Dungeon games by Spike-Chunsoft, Rumble games by Ambrella. --- Serebii from the amazing Serebii.net Your #1 Source for ALL Pokémon Games & Anime info as the top online Pokédex & Attackdex!