I was thinking about which pokemon in the seventh gen would be great for gym leaders. It goes as following:
maybe Charchabug, but nothing very special here
nothing special there either
-Sallazle would be pretty destructive for Corey, because of its insane speed and the fact that it can literally poison everything
-Golisopod would definitely be perfect for her, because of her rain strategy. It would become a nightmare for a lot of chalengers
-Mimikyu, because of his fairy typing that protects it from dark-types. Its Ability is insane and it is soooooo cute!
Anything special here
-As for Corey, maybe a Sallazle
-A Toxapex would be a great tank for her
-Komala, with its Comatose ability, would be a good pokemon for Noel
Nothing that is not already made better by one of his actual pokemon, except marbe the Alolan Raichu
-The only dark-type except Silvally and Guzzlord is Incineroar, which is actually pretty nice
-Kommo-o would definitely be great for him, since it has the Soundproof ability, and he actually fights in a field that boosts sound-based moves
-Mudsdale is insane with Stamina
Nothing very special
-Minior, with Shell Smash and a White Herb, would be good, moreover I think Earthquake can get stronger on the Big Top (against electric and rock)
-As for Shade, a Mimikyu
Since the other leaders did not came out yet, I did not put them here.
If you have any other suggestion, don't hesitate to put it in the comments!