The sense I kind of get looking over some of the reviews and descriptions, I start to wonder what critical reception would have been like for a movie critic to walk into Avengers Infinity War and/or Endgame who had no real foreknowledge and without ten years of prior movies to gradually introduce characters, settings, and tropes. Would they hate so much of the writing being referential to the qualities of these heroes that they lack the background knowledge of? That's what this kind of sounds like to me, where the writing kind of assumes that the viewer is already at least decently familiar with pokemon and some of their typical qualities, and may not take the time to take the hand of the fully uninitiated.
That's a fair criticism to throw at this movie's feet, though hopefully these reviews' readers are aware of that. Either way it sounds like even if you are familiar with the pokemon themselves, the writing isn't very standout, which is a shame. I'm still plenty curious and excited to see it myself, but this helps to set my expectations going in.