In Riding the Winds of Change!, Gliscor was caught as a Gligar that had acrophobia and couldn't fly very well. In Chim-Charred!, Gligar was used to battle Paul's Gliscor but was no match for its evolved form and Gliscor knocked it out with Guillotine. In Fighting Fear with Fear!, Gary suggested to evolve Gligar with a Razor Fang into Gliscor so it can overcome these fears. Later on, Ash's Gligar eventually evolved into Gliscor and saved Ash while free-falling in a canyon.
In Mastering Current Events!, Ash used Gliscor to battle Air Battle Master McCann's Scizor and learned Giga Impact and trains with McCann. Gliscor was seen again, but was replaced by Gible. Ash summoned Gliscor from McCann in order to battle Paul in the Sinnoh League. Gliscor had perfected Giga Impact and while training with McCann, it learned Stone Edge. During Ash's battle with Paul, Gliscor battled Ninjask but was unable to overcome its speed and was recalled after Ninjask knocked it into the ground, causing it to become poisoned by the Toxic Spikes that was left behind by Paul's Drapion. Gliscor later battled Drapion and burned it using Fire Fang, defeating the Ogre Scorpion Pokémon. However, due to its exhaustion and the fact that it had been affected by Toxic Spikes, Gliscor was defeated by Electivire.
It is assumed to be at Professor Oak's Laboratory. However it is also possible that it may have returned to McCann for more training. It reappears along with all of Ash's Pokemon in an upcoming episode of Pokémon Black and White: Adventures in Unova and Beyond.