Seeing Ash and Sewaddle were in danger, Burgh sent Leavanny, who pulled them up from a waterfall using String Shot. Seeing Sewaddle's "cloak" got ruined, Leavany managed to craft a new one using new leaves, pleasing Sewaddle.
When Ash's Swadloon defeated Burgh's Whirlipede in the Gym Battle, Burgh sent Leavanny as his last Pokémon. Leavanny immediately used Protect against Swadloon's Energy Ball. Leavanny enveloped Swadloon with String Shot, but Swadloon freed itself with Razor Leaf. However, with Leaf Storm and Hyper Beam combination, Leavanny defeated Swadloon. Ash sent his Pikachu (even if Oshawott wanted to battle instead). Pikachu started off with Thunderbolt, but missed. Leavanny used Protect against his Iron Tail attack and used Leaf Storm, which collided with Pikachu's Thunderbolt. In that distraction, Pikachu was wrapped by String Shot and couldn't move nor attack properly and got hit by Leaf Storm. Pikachu tried to attack with Thunderbolt, but missed and got hit by Leavanny's Leaf Storm. This caused Pikachu's strings to be cut off. Leavanny tried to bind Pikachu with String Shot, but Pikachu avoided the attack and used all four moves it knew to defeat Leavanny, thus making Ash win the Gym match.
After Ash's Swadloon evolved into a Leavanny, Ash remembered Burgh and his Leavanny, who could craft leafy clothes for Swaddle, whose "cloak" became ragged.
Ash remembered battling the Unova Gym Leaders, including Burgh and his Leavanny, the night before he entered the Unova League.