Pokemon X and Y Walkthrough: Pokemon Trainer AZ
After defeating Diantha, she registers your Pokemon in the Hall of Fame. It stores every team used to beat the Elite Four. Flash forward a few days and there's a parade in Lumiose city honoring you and your friends. Professor Sycamore presents you the Honor of Kalos for the bravery needed to take down Team Flare. After the festivities conclude, AZ appears for a battle. It isn't very difficult because he only has three level 60 Pokemon.
Pokemon Trainer AZ
AZ finally gets reunited with his Floette after all these years. It was waiting for him to become the man he once was.
This ends the main quest. From here, you can go to Kiloude City by way of the trains found in Lumiose City. There are also a set of Looker Missions found in Lumiose City as well. I think they're one of the highlights of the game. Looker is a very interesting character.