While resting at a Pokémon Center with Nico, Chester overheard a conversation of Ash and his friends about the Battle Chateau. Since they were on their way there, Nico and Chester decided to approach them and tell them more about the place. Ash then decided that he wanted to go there and see it for himself.
While Nico had already battled frequently at the Battle Chateau and earned the rank of Baron, Chester was new there, and so Nico wanted to introduce him too. Inside the Battle Chateau, the group was welcomed by Molly and Duke Turner. Later, Nico's battle request was accepted by a Trainer named Farrell. Chester watched his brother's victory, which elevated his rank to Viscount. Turner then announced that the next battle would be between Chester and Ash. Before the battle, Molly informed both Trainers the winner would gain the rank of Baron.
For the battle, Chester chose to battle with Fletchling, while Ash chose to battle with Pikachu. Ash took the initiative by having Pikachu use Thunderbolt. Chester chose to have Fletchling dodge it with Agility. Fletchling then dodged a couple of Electro Balls and went on to use Feather Dance, lowering Pikachu's Attack. Chester then had Fletchling use Steel Wing, which Ash tried to counter with Pikachu's Iron Tail. This went on for a while, with Iron Tail not doing a lot of damage due to Fletchling using Feather Dance before. After gaining a bit of momentum, Ash had Pikachu defeat Fletchling with Thunderbolt, causing Chester to lose. Although Chester lost, Nico assured they would train together to win next time.
Afterwards, he watched the battle between Viola and Grant. After that battle, Nico and Chester said their farewells to Ash and his friends, and they promised to meet up again sometime.
Fletchling is Chester's only known Pokémon. It first appeared on Chester's shoulder when he and Nico approached Ash and his friends. At the Battle Chateau, it went up against Ash's Pikachu. It managed to dodge Pikachu's attacks with Agility and lower his Attack with Feather Dance. Although Pikachu's Iron Tail didn't do as much damage because of this, Pikachu eventually managed to gain momentum and defeat Fletchling with Thunderbolt.