It's been advertised forever. If there was a case, Nintendo lawsuit-happy lawyers would have taken them down by now. It was never a secret their design shared aesthetic with Pokemon.
Reading the article explains that it's not that their aesthetic is shared, it's that some of the models are extremely similar to S/V models, beyond the likelihood of coincidence, and Nintendo plans to investigate if it's coincidence or actual asset theft.
Screenrant Article here from a day ago.
It does still state that Nintendo intends to investigate, but most of the stolen/copied asset claims have been refuted or rescinded. With the main "they stole assets" person admitting they fabricated the proof because they hate how Palworld glorifies animal abuse (which is extremely ironic to me because no one had a problem when Pokémon was cockfighting for children)
Yeah, if one of the most litigious gaming companies out there hasn't filed a suit against them, then I think they might be ok, unless they can somehow prove parts of assets were used.
The closest Nintendo has gotten to legal stuff was against a modder for Palworld who used Pokemon and put the mod behind a paywall and I'm pretty sure if they didn't charge they might have been left alone maybe.
Now that the game is out the assets can be ripped and directly compared, and so far the comparison shown by some people on the Internet have shown that many base models are nearly identical which is probablistically near impossible
If you go to the account that this account uses for proof, you'll see that the user (byofrog) admitted that they fudged the specs to make them look identical. This is not a one to one comparison
The only way to tell is to open up both models and look at individual points of the 3d mesh. If their positions in 3d space match up to, say the hundred-thousandth of a decimal, then it is a copy.
But if the model was scaled or rotated or whatever, there would be no way to prove a case because there wouldn't be a match.
The same thing was done to prove games was lying about copying models from previous games when they claimed that it was too difficult to add all previous monsters into different games because their converter tool was giving them issues.