Sierra

It's hard to think of something more difficult to budge than a mountain, but Sierra sure comes close. She's notorious within the league for being fantastically stubborn, and she's said to be the only person who can out-argue even Hercules and Siegfried. Championship hopefuls facing the Elite Four find her a harsh opponent and struggle to bring down a team of Rock-types every bit as indomitable as their trainer; Sierra just smiles the whole way through. As far as she's concerned you can't call it a proper win unless you've really clawed your way to victory. The same bullheadedness and bellicosity that intimidates her challengers and sometimes gets her into trouble also fuels a fierce loyalty to her friends, however.

Sierra's father Landon was Etaoin City's gym leader for many years before announcing his retirement a little while ago. She's been on a crusade to get him back into the gym and back to real training ever since she found out that by "retirement" he actually meant "getting into Pokémon Contests". No Belmont wastes their time with that kind of boring nonsense!