In ORAS, in Dewford Hall, there's all those crazy bandwagoners who freak out over Potion Contests or whatever, and you can change whatever those hipsters are into by speaking to the lad outside. But that's not the point! The first time you go in there's nothing special. But later in the game, if you go back, a Collector appears. He gives you the TM for Sludge Bomb. At what point in the game does he appear in Dewford Hall?