From Bulbapedia, the community-driven Pokémon encyclopedia.
The Kumquat Gym (Japanese: リュウチンジム Liǔchéng Gym) is the official Gym of Kumquat Island. The Gym Leader is Luana. Trainers who defeat her receive the Jade Star Badge.
The Kumquat Gym made its only anime appearance in Pokémon Double Trouble.
The first Double Battle in Pokémon canon took place at Kumquat Gym. In order to gain the Gym's Badge, challengers must use two of their Pokémon to defeat two of Luana's Pokémon simultaneously. The Kumquat Gym itself also doubles as Luana's luxury hotel, and battles are held in and around the resort. The hotel is several stories tall and has a built in battle arena, an artificial hot spring, a tennis court, and exercise rooms for use for both Pokémon and people. The only Pokémon the Gym is known to own are Alakazam and Marowak.