>>53301971The Gym leaders are largely just standing around in their gyms, which puts it at a step backward from Gen 4 and 5 which often had you meeting some Gym leaders outside of their gyms or before it. The best you have is Korrina having the Mega-stone plot and Wulfric needing you to track him down. But Wulfric is also an 8th Gym leader with 3 ice types, so his battle struggles to leave an impression.
Similarly, Diantha doesn't show up remotely as often compared to other champions. You see her twice, and neither is in the context of actually helping to do anything about Team Flare.
Team Flare itself has Lysandre, but four of the five named bosses are girls with visors and different hair colors, and then one scientist. That's more admins than Team Galactic, who have the advantage of being named after planets and having a more even guy/girl ratio. It's like if instead of Saturn, Mars, and Jupiter, you had Mars, Mars but with blue hair, Jupiter, and Jupiter with Green hair.
And of course the rivals. The fact that there's four again means less time for any of them to make an impact beyond their gimmick, which makes them all stand out less in the long term because it's just "the pokedex one" or "the dancing one".
tl;dr Too many characters of certain types, less involvement of characters of other types.