They have nothing to stand on outside of the art if that is true, Else they would have shut down things that are very much closer in scope to pokemon (i.e. digimon, which they tried, and it was dropped, they cant own a art style or game play cycle.), this one doesnt even ape the idea wholesale there is no evolution but the breeding mixes types. And Arc and Zelda would have a few words but again, you cant own a gameplay loop, I mean ask PUBG how that went for them.
They can say and imply a lot of BS on a press release that wouldn't fly on a court filling unless they have hard evidence. They can barely write a cease and desist order to the Pokémon mod creators. They can't do anything beyond that.
The only thing that might be a real wrench in the works for the palworld company, is its said their CEO was talking about using AI and that you could feed it just simple things and get a real workable output. But this could mean anything and it may not have been more then a testing time in house. There was a forum post about the artist(s) that were working on rigging the pals that they said they were able to get them working in under 4 hours after getting them from concept artists. (I havent read the topic, it was just talked about by twitch and general artist Julia (cohhcarnage/dansgaming to name a few of her main outputs) she linked it in a dropped frames episode, and I would think she would be more abreast of these art topics then most nerds on the internet.
Dragon Quest 5 came out before Pokemon and had monster joining you to fight by your side, ain't much they can do about the concept so as you said it's about the art/monster design.