In Showdown on Poni Island!, Mudsdale waited for its Trainer outside the Ruins of Hope. As they left, Mudsdale stepped on a Corsola branch and went berserk. Seeing Mudsdale in pain, Ash had Pikachu use Iron Tail on its hoof, which dislodged the branch. When Hapu became annoyed with Ash, she had Mudsdale kick Ash, Pikachu, and Rotom, which sent them flying to where Gladion and Lillie were. They continued to chase after Ash but were stopped by Lillie.
In A Grand Debut!, Mudsdale was used in Hapu's grand trial battle against Ash, going up against his Pikachu. Despite having a type advantage, Mudsdale was defeated when it was splashed with water, allowing Pikachu to knock it out with Gigavolt Havoc.
Mudsdale is a strong Pokémon, as seen when it managed to withstand three attacks at once before launching a move that easily knocked out all three of its opponents. Mudsdale also tends to go berserk and ignore its Trainer's instructions, like in Showdown on Poni Island!, when it got a Corsola branch lodged in its hoof. However, whenever it is in a normal and relaxed attitude, it follows its Trainer's instructions without question. Mudsdale also seems to share Hapu's views about the island challenge, as it was visibly annoyed with Ash's simple description of the challenge, and upon Hapu's orders, kicked Ash, Pikachu, and Rotom without hesitation, sending them flying.