N and Barry are my favorite rivals for competent teams, unique stories, fun personalities, and they don't feel shoe horned in. Barry is an interesting case since he's a very typical rival and does very little for the plot, and yet he still feels like an important part of DPPt.
The Amazing rivals are ones who have story relevance, fun personalities, and are engaging characters to be around, but aren't necessarily strong trainers or add too much to the games. You could remove Bianca, Cheren and Blue from their games without losing that much, but their inclusion makes it better overall.
Great rivals are a bit more one note personality wise, but they still have a strong story foundation and are fun enough that it's enjoyable to keep them around. I'm only counting ORAS Wally here since the original Wally was a lot blander.
The Good rivals don't really stand out too much overall but also don't lower the story in any way. Hugh is around a lot but he doesn't particularly stand out personality wise. I like that he joins up in a lot of double battles. Silver is classic but still relatively boring overall. Marnie and May are just kinda fine.
Okay rivals don't have much to them but aren't enough to deduct points from the game. They may as well just be regular trainers.
The Bad rivals don't do anything, stick around too much, talk too much, have annoying/one note personalities, and are way too easy to fight. I've never finished USUM so I don't know anything about Hau's champion fight there so I'm speaking from a SM perspective.
Also I should make special note that I may be biased, as Bianca is my waifu.
