>>39216519Blue/Green - Only designed to serve as a rival, no interesting qualities or relevance.
Lance - Just some strong dude who helps you stop Team Rocket once.
Steven - Like Lance, just some strong dude, but you bump into him more than once and also serves as an exposition dump.
Wallace - Flamboyant guy who was made Champion for no discernible reason other than not letting Blaziken sweep most of the Pokemon League.
Cynthia - Only serves as an exposition dump. Has no interesting qualities or importance on the story.
Alder - Actually has a backstory. It's minimal, but it's there.
Iris - Screentime in BW2 is on par with Diantha, and has even less importance as a person/character.
Diantha - Had potential to be included in the story given the theme of Lysandre's plot, but GF wasted the opportunity.
Kukui - Doesn't really count, not being a Champion. You fought him for the right to be the first Champion.
Hau - Like Blue/Green, only designed to serve as a rival, albeit with a different personality.
Alder is unironically the best, but that's not saying much.