Not sure how it works in Japan, but in many nations you have to file for a patent before or pretty soon after you release your product / service. In the US I think there’s a 1 year grace period. It’s a pretty common sense thing that stops whole businesses springing up and then being shut down by patent creation just like we are seeing here.

There are many games out there now that involve catching monsters and making them fight for you, Nintendo would be shutting down 100s, if not 1000s of developers if they wanted to go ahead with this and have it be taken seriously.

Anyone that has played Palworld will tell you that it much more resembles ARK than it does any Pokémon game or experience anyway.