• English / United States: Ash's Gengar
• Japanese / Japan: サトシのゲンガー
• Japanese (Romanized) / Japan: Satoshi no Gangar
• Japanese (TL) / Japan: Satoshi's Gangar

Ash's Gengar was caught at the Sakuragi Institute in the Kanto region. Gengar's Trainer was its previous Trainer three years prior to Ash Ketchum catching it. Gengar's Trainer ran into Ash Ketchum while Ash's Gengar was attached to Ash Ketchum's shadow. He got rid of Gengar because he was very unlucky. He couldn't win a battle, and every Pokémon he tried to catch would get away. He also would fall down the steps and he'd lose things all the time. He blamed all these mishaps on Gengar's curse. He left Gengar at the building that years later would become the Cerise Laboratory. Since then, he thinks his luck had changed without Gengar.

Pokémon World Championships Battle VS Visquez

This was the first battle for Gengar as one of Ash Ketchum's caught Pokémon. The combination of Ash's Pikachu and Ash's Gengar during the Pokémon World Championships match was too much for Visquez's Raichu and it was defeated with a powerful Psychic attack. It then faced Visquez‘s Electrode. A lot of challengers come to the Vermilion City Gym with Ground-type moves and to deal with that, they trained Electrode to use Magnet Rise to control the battlefield. Despite defeating Ash's Gengar, Ash's Pikachu was able to defeat it to win the match.

Pokémon World Championships Battle VS Marnie

Marnie's Grimmsnarl battled against Ash's Gengar during a Hyper Class Battle for the Pokémon World Championships. The hair on is body is also a transformable weapon that is very effective. Both Trainers had a Dynamax Band on and it was a waiting game to see who would Gigantamax first. Grimmsnarl was the one that ended up Gigantamaxing first while Gengar continued to battle. Realizing that he needed to match its power, Ash got Gengar to Gigantamax. Darkest Lariat turned out to be a bad move for Grimmsnarl as it ended up being swallowed by Gengar causing them to revert to their normal forms. The two charged up their final attacks with Gengar using Shadow Ball and Grimmsnarl using Stomping Tantrum but it was Gengar's move that hit giving Ash Ketchum the victory and increasing his rank to 15.

Masters Eight Entry Battle

Raihan's Flygon battled against Ash's Dragonite in the match that featured Masters Eight on the line. Sandstorm proved to be very effective against Dragonite as it couldn't see where the attacks were coming from for most of the match. It defeated Ash's Dragonite and then battled against Ash's Gengar. It initially used the same battle technique of obscuring its attacks and being able to navigate through the Sandstorm but after Gigantamax Gengar sucked up the Sandstorm, it was quickly defeated.

Raihan sent out Raihan's Goodra after Raihan's Flygon was defeated. It used Rain Dance to make the weather on the battlefield be rainy. It was able to knock out Ash's Dynamaxed Gengar but it ended up being knocked out at the same time.