I can never really sit well with Brionne, and to some extent, Primarina. Not sure what I expected from Popplio, but let's just say I wasn't too excited to find out it would eventually turn into a mermaid. I'm still not completely okay with their designs. Brionne's, especially, is a sin.
I COMPLETELY agree with Brionne. Not really though with Primarina because that one is one of my favourites but the middle form... ugh. I just can’t stand it. I think it looks more like a rejected mascot from some educational kid’s game than a mon. It a shame, because I used to like it when it was originally revealed...