The problem with Rivals is because in game NPCs are a joke, beating them never feels like an accomplishment. Even the "good" rivals revered by this board aren't that great when you look at them in the context of the story.
Blue spends the entire game going on about how much better he is than you despite constantly losing. What he does have going for him is he's always ahead of you as far as progression goes, if you're playing these games for the first time its a real surprise when he's revealed to be the champion.
Silver is not great despite this board's hate of friendly rivals, You're not even working towards the same goal. On top of that he preaches to you about power and discipline despite repeatedly getting his shit kicked in. They rectify some of this in HGSS and explain his motivations. The best part of his arc is when you battle him and he has Crobat finally showing he's come to love his pokemon.
Wally is actually a good Rival, his appearance at the end of victory road is memorable, despite not appearing in much of the playthrough, his story doesn't revolve around you.
May/Brendan are probably the worst rivals yet, once again your rival doesn't seem to aiming towards the same goal or anything really, they provide no challenge and always on your heels as opposed to Blue.
Barry despite how much hate he gets does have a rival feel, you friendly, but not too friendly, he has a desire to beat you.
Maybe ill do the other shitters later.