Here are some fun facts, not about Pokemon but Gamefreak.
Gamefreak does not and never has belonged to Nintendo, they are an independent company. However, even though they make the games they only own one third of Pokemon's copyrights, the other two thirds of the rights belong to Nintendo and Creatures Inc.(Who actually is a 2nd party company to Nintendo unlike Gamefeak). This is why the Pokemon games have never been on non-nintendo systems outside of some mobile phone/smartphone titles, some Sega Pico edutainment games, and some PC CD Rom "games" that were mostly available in the late 90s.
However, since the company itself does not belong to nintendo, they have and still do make games for non-nintendo platforms. One of their most famous is Pulseman, a platformer exclusive to the Sega Mega Drive/Genesis, but they also made Click Medic for the PS1, Tembo the Badass Elephant for PS4, Xbox One, and Steam, and Giga Wrecker for Steam(unlike past games Giga Wrecker is not only developed but also published by Gamefreak, so it has the budget fitting an indy title since they are, even with Pokemon's success, a small-sized company that usually gets most of their games' budget from much larger publishers, usually Nintendo or Sega)