According to Nintendo: "This lawsuit seeks an injunction against infringement and compensation for damages on the grounds that Palworld, a game developed and released by the Defendant, infringes multiple patent rights."

The entire statement: https://www.nintendo.co.jp/corporate/release/en/2024/240919.html

They finally did it. After everything that was pointed out on the internet about the blatant copy-paste of some of their assets/animations and such ...

I guess it was moreso a diligent work to document whatever they needed to make a solid case for themselves.

They are apparently suing for copying patented game mechanics (maybe something like the obvious Pokeball catches?), not designs or anything of the sort. Which honestly they wouldn't win anyway.

Thinking on it, it's likely that since this is the stuff they can legally patent for their own purpose. Anywoo, this is going to be a must watch moment

It seems like there's a very specific patent for the Pokeball catches, so my guess could be correct after all. I suspected it had to be something from Red & Blue since that's when Nintendo would be involved personally and not just TPC/GF.

Why not? Based on my very limited knowledge of ip law, it seems like they would have a case. 

These are copyrights, not patents (which is what is being litigated here), and they would have to be absolutely blatant for there to be a case. Think closer than what Master Chief and Doomguy look like. You can't reallly copyright an overall style or vibe.

Ah yes, you are correct. If they were suing over character design that would be copyright. That said, I do think that the designs are Palworld are similar enough that one could argue that they were intentionally designed to cause market confusion. Not saying it's a slam dunk argument, but I think there's a case for it. Then again, apparently Nintendo opted not to make that case, so what do I know. 

I guess they needed a good amount of time to evaluate every possible patent or copyright – and in the meantime the compensation for damages have also grown. Probably the developers of Palworld can already file for insolvency... don't mess around with big N.

I'm not a lawyer but I regularly am a SME on patent cases.  I find it to be a giant PITA and what seems obvious never is.  Just my 2 cents.