Nintendo does not offer for sale, sell or distribute its games for its consoles or handhelds digitally other than from Nintendo eShop.
If you see games offered for download using Peer-to-Peer networks, or by clicking on links to files hosted on third-party platforms, the content that you are accessing is an unauthorised copy (i.e. a pirate copy). Pirate copies of game files are often referred to as “ROMs”.
The uploading and downloading of pirate copies of Nintendo games is illegal.