Elementalist

Elementalists discover and develop an affinity to a certain Pokemon Type. Every Gym Leader in Kanto and Jhoto history, with the exception of the current Viridian City Gym Leader, Blue. Elementalist Trainers tend to grow to reflect the Type that they specialize in, so each Pokemon Type corresponds to a different skill tree and set of skills. It's not uncommon for a Trainer to take an Elementalist Specialization as a secondary class, but specializing in more than one element is rare. The full list of specializations can be found below:

Normal -- Wildcard

Fighting -- Blackbelt

Flying -- Aviator

Posion -- Ninja

Ground -- Mountaineer

Rock -- Monolith

Bug -- Entomologist

Ghost -- Haunted

Steel -- Knight

Fire -- Kindler

Water -- Diver

Grass -- Flower Child

Electricity -- Engineer

Psychic -- Psychic

Dragon -- Dragon Tamer

Ice -- Frost Witch

Dark -- Rogue

Fairy -- Fae