I think you could be right, but it depends on the details Nintendo comes out with. I remember people were saying that they thought certain Palworld monsters had been ripped from the Pokemon games and recolored - if Nintendo can demonstrate that, then that’s a slam dunk for them.

But if it’s just creature designs and collecting them, then I just don’t think that “a cute monkey with green fur” is a novel enough concept to be defensible against someone else doing something similar.