From Bulbapedia, the community-driven Pokémon encyclopedia.
Kalos Canyon (Japanese: カロスキャニオン Kalos Canyon) is an anime-exclusive location in Kalos, featured in Battles in the Sky!. It is located in Route 11, between Geosenge Town and Shalour City. It was formed naturally over the course of tens of thousands of years.
The winds blowing through the ravines in the canyon turn into rising air currents, and as such it's an ideal spot for Sky Battles. There is a center nearby specially for Sky Battles, where Trainers can rent Sky Battle suits and practice in air tubes. The actual Sky Battles are held over the canyon.
Ash and his friends came across Kalos Canyon and witnessed a Sky Battle going on. Afterwards they went to the Sky Battle Center, where Ash, Clemont and Serena rented Sky Battle suits. Later, Ash had his first Sky Battle at the canyon against a Trainer named Moria and her Talonflame. He first used his Hawlucha, but lost. He then used Fletchling, and managed to win when Fletchling evolved into Fletchinder.
In A Towering Takeover!, Grant was shown there, watching Lysandre's broadcast from Lumiose City.