I can see Aloe having this pokémon as her main powerhouse in the end. It seems fitting for her and plus it's a normal type so it works. In addition to it suiting her type, many people have mentioned Aloe looking very buff or big which had lead to predicting she would become a rock type gym leader. Buffalon is also a buff and fierce looking pokémon which would suit her all the more.
We know Dento has Yanappu as his main, but I've been wondering what his other pokémon for the battle will be too as well as his partners, Kon and Poddo. Being gym leaders with the grass, water and fire types, I can only assume they would be some of the early game pokémon of each type.
I was thinking about this earlier and decided to bring it up. If we are able to have rematches with the Gym Leaders, I think it would be ideal to have Dento's, Kon's and Poddo's main powerhouse evolve when having a rematch with them. It'll show they've been training and hopefully, be more of a challenge for us. I'd like for them to prove their challenge worthy too. Their pokémon could have strategic moves basing off of their type and main stat. Say if Yanappu was a fast pokémon or good in speed, maybe some moves revolving around speed would be nice. More useful items other than a potion or any other healing item will help as well. Not saying this has to be for those three alone, but goes for the other Gym Leaders as well.