We don’t think Nintendo cares so much that people are playing Pokémon Prism. However, they do not want a use of their franchise that requires the use of ROMs of their own work to be easily available. ROMs are not illegal per se. If you make your own backup of a copy you own for your own use and then patch it, then it’s not. But most people who play those games don’t own the original at all. And download those off the internet.
Nintendo was right to shut down Pokemon Prism
The patch is out there for Pokemon Prism and people are still able to play it because Nintendo let it happen. If they really didn’t want you to be able to find it, they would have sent a cease and desist a long time ago. This patch was being worked on for YEARS. Same for AM2R which in itself didn’t require any ROM. But which still used the copyrighted namesake and likeness.
We’re pretty sure that they HAVE to take those legal steps to protect their branding. Otherwise, if they let it slip, anyone could come out and make a commercial project with the name of a Nintendo property on it. And a court of justice could find in favor of whoever made it. Because of a precedent where Nintendo let their brands be used and didn’t do a thing.
If they really didn’t want people to play those games, such projects would be stopped much earlier on. And not when they’re already out in the wild. For instance, Nintendo never stopped Tomato from putting out a translation patch of Mother 3. Because at the end of the day, it doesn’t turn the game into another product. It just makes it accessible. We believe the fact that the franchise is dead outside of Japan also means that patch doesn’t put their business with that game in any danger.
Source: Kotaku