Nintendo had registered the patents in a filing not long after Palworld's release, setting the stage for the lawsuit.
How is that even legal? Decades after releasing something, a competitor comes along and releases their product, so you decide "now's the time to file a patent" and you can kill the competitor. That should create a very unstable business environment as no new business can be safe when making a patent check as they can be filed after you created a product by somebody else. It makes no sense.