After defeating Roark, head back through Oreburgh Gate to Jubilife City. As you enter, you'll encounter Professor Rowan and Dawn/Lucas being harassed by two Team Galactic Grunts. You and Barry will team up to battle them. This is your first taste of Team Galactic, the main antagonists of the game.
After the battle, you'll receive the Fashion Case from a TV reporter. You can now participate in Super Contests! Head north from Jubilife City onto Route 204.