Where do you find the gym leader marlon in Pokemon white and black 2?

In Pokémon White and Black 2, Gym Leader Marlon can be found in the Humilau City Gym. This gym is located in the coastal town of Humilau City, which is accessible after defeating the Elite Four. Marlon specializes in Water-type Pokémon, and players must navigate a unique water-filled puzzle to reach him. Defeating him awards the player the Wave Badge.