Alright, OP here. Let me clarify my listings, I apologize for not doing that in the first post.
>Hugh
Yeah yeah MUH PURRLOIN and all that. But Hugh was the first rival since Barry who actually FELT like a rival. You compete with each other to tell who's stronger and to better yourselves. And he's actually GOOD. The Purrloin backstory is both dumb and sweet; he really cares about his family, specifically his little sister. But he does overexaggerate a lot and treats Plasma like they're worse then, say, Team Rocket. Also best rival theme
Blue and Barry are the same case, childhood friends, good team compositions, good themes counting Blue's champion theme.
Barry was a bit too much cuh-rayzee: he obviously fights Galactic because they're bad but they don't flesh him out. Same with Blue, but to be fair, it was the first games. All we have to go on is the rumors about his Raticate. He does win for his snarky personality and superiority complex, though.
Cheren is in decent tier because he grows over the course of the game. So is Bianca. Both of their teams are underwhelming, though, and if I recall Cheren takes everything too seriously and doesn't just focus on bonding and improving his team. Bianca has good character, and finds who she really is. Silver is a wild card who sets his rivalry with everyone. He's kind of edgy though, which is why he's not any higher up.
Brendan and May don't exist. Trevor and Tierno do, but they aren't REAL rivals. I like their character development more then Serena or Calem's, and honestly, their teams are better.
Calem and Serena are the worst fucking rivals. Terrible teams, "abloo-bloo why do you always win I'm so bad I shouldn't make memories with my friends because I lose too much", and just bad rivals. Serena is cute and that's all she gets.
Wally is the hero Pokemon deserves.
