What Gym Leader's Ace would you replace?

Which aces of Gym Leaders do you believe are unfitting, and what would you have them use instead?

Let's please limit this discussion in regards to PERSONALITY rather than REGION. It's clear to many people that Johto has a lot of missed opportunities in giving their aces Kantonian rather than Johtonian Pokemon, and I would rather not have comments like that making up the majority of the ones here. Moreover, I think it's important to see these gym leaders as characters rather than simply specialists representing a specific region.

Personally, I don't think Houndstone fits Ryme super well as her ace. I think Gholdengo or Gimmighoul would be a better fit for her rapper theme and general aesthetic.