>>41568796>>41569435>>41569775Despite the weird legal mess that is ownership of Pokemon, the buck ultimately stops at Nintendo because they own the trademarks for the Pokemon name and all its characters. There is no Pokemon without Pikachu. There have been times where Nintendo has twisted Gamefreak's arm, such as having them scrap Gray to make Black/White 2.
The real reason Nintendo does nothing is because there's no need to. It's easy money for everyone involved. Nintendo doesn't take pride in all its products, see the NSMB games.