I like the interactions between Georgia (Iris's rival) and Burgundy (Cilan's rival) during the Unova tournament arcs in the anime. For some reason I found them to be incredibly funny, and I'd watch a show just about those two doing stuff.
Their interactions were funny, especially with them thinking the other is nuts for how much they don't like their rival when they're just as extreme about it.
Though I think the Gen V rivals could have been written better (mainly Ash's), I do find Georgia and Burgundy to be the more interesting rivals for that saga. For one thing they were rivals for the side protagonists. "So? May and Dawn had rivals" you say. Yeah, but they were secondary main characters. Let's me honest here, Brock, Tracey, Max, Iris, Cilan, and currently Clemont and Bonnie are "side protagonists". They're part of the main crew but they don't really have a story arc which is given much focus. They don't really get rivals since their stories don't require them. So it's interesting they gave Iris and Cilan rivals, and in order to do so they had to give the rivals more unique motivations.
Hmm, Iris wants to be a Dragon Master and Cilan a S-Class Connoisseur, who would be their rivals? Another Dragon Master and someone wanting to be a S-Class Connoisseur? That would be boring and wouldn't make much sense as why would their goals conflict with theirs? What if Iris rival was a trainer who hated Dragon-types and made it their mission to defeat dragons, a "Dragon Buster"? As for Cilan, what if his rival more personal, like a not-so-good trainer that challenged him to a Gym Battle and Cilan told them that the bond with their Pokemon was weak and they then became a Connoisseur to try and prove them wrong.
I could go more in-depth but I'll just say overall I liked them as foils for the protagonists they were rivals with... I just wish they got a better conclusion. They made their last appearance at a tournament arc, the Pokemon World Tournament Junior Cup (
BW090-93) so they only got a few words with their rival before moving on into oblivion. Georgia was okay, she told Iris she was going to train harder to defeat her Dragonite but you felt the two had grown respect for one another. However Burgundy acted obnoxious to Cilan as she did from the start, she experienced no character growth. There really needed to be an episode for each of them to tie together any loose ends. Like for Burgundy, I feel we needed an episode where Cilan helped her become a better Connoisseur. Like in her theoretical last episode she's having trouble studying for her B-Class exams, Cilan helps her, she passes and becomes a B-Class Connoisseur, and they end on a more respectable note.
As for Georgia, had Iris made a visiting reappearance in Kalos (which doesn't look to be the case especially with them wrapping up Gen VI) I think Georgia should have also reappeared. The introduction of Fairy-types would have made for an interesting new part to their rivalry, Georgia finally being able to get on even ground with Iris (would also be interesting to see Iris's reaction to Fairy-types, I would feel she would act unreasonably hostile to them much like she's unreasonably afraid of Ice-types).
But Georgia's and Burgundy's last appearance being disappointing is far from the many problems with BW saga.