Ash's Gligar evolved into Gliscor in order to save Ash from a fall. It used the Razor Fang Ash received from Gary to evolve.
On their way to Daybreak Town, Ash and his friends met the Air Battle Master, McCann. In order to test his Gliscor's strength, Ash asked McCann to have a battle with him. McCann accepted, but the opponent's Scizor proved to be really strong, as it used the wind currents to dodge all of Gliscor's attacks. The loss made Gliscor really sad, but also motivated it to train harder overnight on 'reading' the wind movements with Ash's help. During the rematch battle against McCann, Gliscor learned Giga Impact, which aided it in putting up a better fight than in the previous battle. Even though in the end it still lost, the Air Battle Master was really impressed by Gliscor's improvement and thus offered Ash to train it. After Ash noticed his Gliscor's will to become stronger, he accepted McCann's offer and left the Fang Scorp Pokémon in his care.