In terms of what kind of t they use, I'd say Whitney is one of the greatest out there, really. Her team consists of only normal-types, which, yes, are quite easy to take down with fighting-types, but at the same time, they're also quite a tank. For me, one, big threat was Milktank. It was simply tough to damage, and once you manage to get this Pokémon to a low amount of health, it would recover itself immediately with Milk Drink, which, for me, was very upsetting. Same goes for a lot of other people as well, I'm sure. It also knew Rollout, if I remember correctly. While the attack doesn't cause much damage at beginning, it becomes more and more powerful each time it has been used, and once you're up to a certain limit, you'd be able to knock out almost any opponent with it by only one hit.
Design-wise, I'm very much fond of Winona. Although she does wear a pretty complex outfit, it resembles her a lot, considering that she specializes in flying-types. Alongside, I'm also a pretty big fan of Flannery, as well as Brawly. Hoenn's Gym Leader designs were all pretty stunning, if you ask me.