Best Wishes! is my least favorite series and I hate that because I loved many of the characters. Langley, Cabernet, Kenyan and Bel are amazing side/rival characters but their stories (aside from Kenyan) were horribly handled.
Langley's rivalry with Iris was interesting to watch when they were not battling. Aside from Beartic vs Excadrill, all their battles were a mess and she ends up being defeated by DEMgonite and she just... disappears. She only had a minor win on screen to show her "Dragon Buster" rep and she never impacted Iris' growth and flaws.
Cabernet suffers even worse with Cilan. She was a delight when she was on the screen but was complete fodder everytime she battled (and she was blatantly robbed against Iris on the Donamite Tournament). Her character never advanced, she stayed a lower class Sommelier all the time and was only shown studying hard on the last ending haha
Bel was amazing during her first appearence and was horrible on the Don Battle with her Zorua obsession (even trying to trade her "precious and valuable partner" Pignite) and the way they handled her story with her father on Nimbasa. She gets funny again afterwards and gets a great showing on the Donamite, only to become worthless on the league thanks to the annoying kid.
Kenyan was the only one who was great all the time. His team, his rivalry and his development (as little as it was) were nice and got some of the best battles on the series (except for the horrendous thing against Emolga). The Nurse Joy/Audino cosplay he did with Sawk is an outstanding moment.
Likewise, Ash's team suffered the same fate. Oshawott never evolved beyond a comic relief, Snivy's story went nowhere except for a small bit on Tepig's evolution, Boldore and Palpitoad were bland after their first episode and Unfezant and Leavanny only had like 2 great moments during the entire series. Aside from their designated "big" win, most of them never achieved anything worthwhile battle-wise. Boldore/Leavanny/Unfezant had to evolve AND learn the exact attacks they needed mid-battle to win (although Leavanny's battle against Sawk was amazing!). Oshawott only won by comic relief/luck... Palpitoad at least got some decent battles, I guess. Snivy's battles were special- if Attract worked, she won. If Attract failed, she lost- the only exception was the amazing battle against Pawniard. Pignite, Krookodile and Scraggy were the only consistent ones.
BW! had awesome potential :(