Mistralton City Pokémon Gym Leader: Skyla "The High-Flying Girl"
Mistralton Gym is designed like a military hangar.
Pokémon Black and White
The player must first go talk to Skyla at the top of the Celestial Tower and ring the tower's bell before she'll return to the Gym so it can be challenged.
The inside of the Gym is full of cannons which the player must use to make their way to Skyla. Most of these cannons help the player to progress to Skyla; however, some will blast the player back to a Trainer. The cannon behind Skyla works as a shortcut back to the entrance.
Pokémon Black 2 and White 2
The interior of the Gym has been redesigned to feature large fans at the back of the Gym that can blow the player across the room. Upon attempting to reach Skyla, the player can hide behind walls to avoid the heavy gusts of wind from the large fans. After defeating Skyla, a large fan that stands behind Skyla blows the player out of the Gym.
In the anime, Mistralton Gym appears to draw major inspiration from its game counterpart, though it does have a dirt battlefield. It has a cannon that can shoot Skyla into the air and explode into confetti whenever she makes her landing. The Gym also has hoops strung up onto balloons that can be left to float over the battlefield during the Gym battle.
The Gym first appeared in Cilan Takes Flight! when Ash and his friends first arrived in Mistralton City and found out that Skyla accepted challenges outside the Gym and played out the battles in her head in mental simulations she referred to as "Air Battles". Her grandfather and the former Mistralton Gym Leader Miles explained that Skyla had lost her motivation as a Gym Leader, and no longer accepted battles from Trainers in order to get more time for her hobby as a pilot. Infuriated, Cilan challenged her to a battle, which she accepted, feeling a battle between Gym Leaders would be more exciting. Cilan ended up losing the battle, just as she had predicted. Ash then challenged Skyla as well and insisted that she faced him in a proper battle. She reluctantly accepted, and in An Amazing Aerial Battle!, Ash managed to defeat her and earn himself the Jet Badge, with his Tranquill evolving into Unfezant during the battle. Afterwards, Skyla agreed to take part in actual battles instead of Air Battles from then on, much to Miles's relief.
Pokémon used in the Gym
Used by Miles
It is unknown what Pokémon Miles used in his Gym battles.
Swanna is one of Skyla's three Pokémon. It was first used in a Gym battle against Cilan. It struggled a bit battling Stunfisk which it had a type disadvantage with and was also burned by its Scald. However, thanks to its Aqua Ring, it was able to overcome its burn and defeated Stunfisk.
The Mistralton Gym appeared in Up in the Air and The Battle Within, where Black battled Skyla in a Gym battle. After being pushed down from the Celestial Tower by Skyla and carried into the Gym by her Swanna, Black was fired around the Gym by its cannons before finally landing into the one near Skyla. During the battle, Skyla told Black she would have the cannon blast him straight back to Nuvema Town if he lost. Luckily for Black, he won the battle, but Skyla departed to Nacrene City with the other Gym Leaders without handing him the Badge. However, the cannon Black was in then fired him out of the Gym and onto the top floor of Celestial Tower. After Black rung the bell at the top of the tower, Skyla sent her Swanna down to him to give him a Jet Badge as a proof of his victory.
Pokémon used in the Gym
Swoobat was first seen with Skyla in the cargo plane while she delivering package in Nimbasa City. Later, it was used to battle Black in a Gym battle and was defeated by his Nite.
Swanna was first used to battle Black in a Gym battle. In the battle, Swanna defeated Black's Nite and was defeated by his Costa. Later, it was used to deliver Black his Jet Badge and took him to Nacrene City to help protect the Dark Stone.
Unfezant was first used to battle Black in a Gym battle. In the battle, she managed to drive his Costa back into his Poké Ball but was defeated by his Tula. During the battle against the Shadow Triad, Unfezant battles with Lenora's Pokémon to protect the Dark Stone.