There are only two things Dragon Quest V and Pokemon have in common; monster taming through battle and they're both turn based RPGs.

Have you played or seen TemTem? It's literally Pokemon in every way, from mechanics, level design, to even how and what kind of moves the Tems can learn.

Nintendo goes after even the smallest infringements, so since they've never gone after TemTem it tells me the patent isn't "monster catching RPG". It's more specific than that, and Palworld somehow infringes on it. As of yet we can only guess what the patent is.