As someone with minimal pokemon knowledge, only played two due to being older and not having Nintendo consoles really, I thought this game was a spin off till I realized no big pokemon or Nintendo logo anywhere. They must have threaded the needle to avoid that copyright infringment.
They’ve done a great job and nailing the art style modern Pokemon games should have had, while being distinct enough to avoid any serious chances of a lawsuit winning.
Modders will be the ones running afoul of Nintendos lawyers.
Nah, once you start distributing the mod, be it free or not, it's copyright infringement. They can't sue you for the profits made, but they can still force you to take it down and pay reparations for any potential damage to their IP, as stupid as that may sound.