First of all, we don't know if Azumarill is Fairy-type, either. Second, even if it is, it wasn't at this point. Magnemite from Gen I are listed as pure Electric.
The Humilau Gym made its anime appearance in The Road to Humilau!. It is a seaside Gym with a rectangular battling field having two raised platforms on the opposite ends. A Trainer named Cameron challenged Marlon for a Gym battle and won, earning himself the Wave Badge, and completed all the eight Badges required to participate in the Unova League.