GR-3 is found here at the beginning of the game, and has the three ladies from the club trapped in a cage in the water. Joshua escaped and will battle the player in the side room, though this is an optional battle.
Upon defeating GR-3, he will free the ladies and leave the club. When the player goes to the entrance room from here, Ronald appears to mention that GR-3 dropped booster packs, and takes the Island of Fossil one while giving the player a Legendary Power pack. If the player exits and returns to the club immediately, Sara is also available to battle in the main hall, as well as Joshua, while the others are unable to battle.