Ash caught Gliscor as a Gligar in Riding the Winds of Change! It, along with many other Gligar and a Gliscor had become trapped in a city after being blown there by a violent windstorm. Gliscor's attempts at using sonar to navigate out of the city were blocked by the tall buildings, and only served to attract more Gligar and the Pokémon soon formed a pack.
The pack survived by picking fruit from trees and stealing food from humans. After Ash and his friends helped the pack, Gligar decided to travel with Ash, allowing him to capture it.
Gligar seems to have a habit of sticking out its tongue and winking when appearing. It also has the tendency to crash land on top of Ash due to its inability to glide properly. It would also cry when scolded by Ash as shown in Chim - Charred! and Fighting Fear with Fear!. Not only that, Gligar seems to be a crybaby of sorts, tearing up very often, especially in fear. As a Gligar, it was terribly afraid of heights. Additionally, Gligar seems to be extremely eager to win Ash's attention and approval.
It evolved into a Gliscor in Fighting Fear with Fear! in order to save Ash from a fall. It used the Razor Fang Ash received from Gary after Gligar had a practice battle with his Umbreon. It appears to have kept its personality traits even after evolution, as it still cries when scolded by Ash and also winks and sticks its tongue out.
Since evolution, Gliscor has been used in more battles. In Aiding the Enemy, Gliscor was used as a sparring partner by Torterra to help illustrate how Grotle could deal with its reduced speed. In Barry's Busting Out All Over!, Gliscor battled Barry's Roserade and the battle ended in a tie, with both Pokémon knocking each other out at the same time. In A Breed Stampede!, Gliscor learned Fire Fang after being hit by an Ice Shard from Piloswine, and is revealed to have learned Screech some time off-screen. In Dealing With Defensive Types! it was used in its first gym battle, against Byron, defeating his Bastiodon, earning Ash his Mine Badge. In Sliding Into Seventh! it was used in the gym battle against Candice, where it was easily defeated by her Snover.
In Pedal to the Mettle!, Gliscor battled Paul's Torterra in Ash's full battle against Paul. Although it was able to cause a good amount of damage as well as using its speed to dodge Torterra's attacks, it couldn't escape Giga Drain, as a result being weakened while Torterra's health was restored. Ash then decided to recall Gliscor, only to use it again against Torterra later on where it was defeated after being hit with Frenzy Plant.
In Mastering Current Events!, Gliscor battled against McCann's Scizor and lost. After training with Ash it challenged Scizor to a rematch. During the battle, Gliscor learned Giga Impact, and although it improved overnight, it eventually lost. Ash then left Gliscor with McCann for further training. It returned to Ash's party in DP185 for its Trainer's battle against Paul in the Suzuran Conference.
It was seen training alongside Ash for his upcoming battle against Paul in DP186, where it was revealed to have grown significantly during its time with McCann. It was also shown to have perfected Giga Impact in a practice match with Dawn's Mamoswine. In DP187, it battled Paul's Ninjask and was shown to have learned Stone Edge while training with McCann. Unfortunately, it was not enough to defeat Ninjask, and so was recalled when it began to show signs of tiring. Ash sent it out again against Paul's Drapion later in the battle, where it was shown to do quite well, hitting Drapion with a powerful Giga Impact, then attempting to strike it with X-Scissor. In the following episode, Gliscor put up a tough fight against Paul's Drapion. Even though Drapion had knocked out three of Ash's Pokemon, Gliscor was the one who defeated it by Burning it with a Fire Fang. Even though it was tiring, it fought against Paul's Electivire. It put up a good fight, but despite type advantage, it lost.