Stunfisk was first seen inhabiting a lake with its friend Palpitoad and a group of Tympole in Facing Fear with Eyes Wide Open!. Palpitoad asked for Stunfisk's help to get rid of Ash and Oshawott as it viewed them as intruders. Stunfisk managed to get them out of the lake and planned to guard against them, but Cilan used his fishing skills with his special lure to catch and pull Stunfisk to shore. Palpitoad then appeared before the group and had Stunfisk fire Mud Bomb at the Pokémon Connoisseur but he managed to evade it. Cilan then lifted his fishing rod in the air and started to spin Stunfisk around, keeping it at bay until Ash was able to defeat Palpitoad. Once he did, Cilan dropped the Trap Pokémon to the ground which, with the combination of dizziness, knocked it out and Cilan captured it.
In The Club Battle Hearts of Fury: Emolga Versus Sawk!, it battled against Luke's Larvesta in the quarter finals of the Club Battle tournament, in which Stunfisk showed the remarkable ability to leap into the air and glide, flapping its fins as wings. Even though Stunfisk's Scald was super effective against Larvesta, Larvesta minimized the damage by covering itself in its own String Shot, acting as a shield. Larvesta then roasted Stunfisk with a powerful Flamethrower, knocking it out.
In Stopping the Rage of Legends! Part 1 Stunfisk was called out to battle Tornadus and Thundurus, blocking a Thunder attack aimed at Axew with its Mud Bomb, it then teamed up with Pikachu to battle. Stunfisk used its amazing jumping ability to get itself and Pikachu into the air so that they could launch a ThunderShock—Thunderbolt combination at the two legendary Pokémon. However, Pikachu was knocked off Stunfisk's back and it was then struck by a powerful Hammer Arm attack, knocking it out.
In Cilan Takes Flight!, Cilan called upon Stunfisk to participate in Skyla's 'Air battle' simulation, during which she predicted that Stunfisk would be defeated by her Swoobat. However, by the time Stunfisk was sent out to battle her, Swoobat had already been defeated by Crustle.
Stunfisk was sent out to fight Skyla's Swanna after Crustle was defeated. Despite ThunderShock being extremely effective against Swanna, it was still able to throw Stunfisk off momentum and into the air with Hurricane.
Cilan had Stunfisk take advantage of its situation and use Scald whilst spinning, showering Swanna in hot water, which burnt it. Stunfisk was then defeated after Swanna used Aqua Ring to heal the burn and hit it with Brave Bird.
In Crisis at Ferroseed Research!, Stunfisk helped a group of Ferroseed, who had become overcharged with electricity, by soaking up the excess electrical energy then releasing it outside.
In Battling Authority Once Again!, Stunfisk battled Akihiro's Cinccino during the second round of the Pokémon World Tournament Junior Cup. Stunfisk won the battle with its newly learned Sludge Bomb attack, allowing Cilan to advance to the semi-final round.
Stunfisk showing its ability to "fly".
In its debut, Stunfisk was quite aggressive, like the other Pokémon living in the lake. However strong Stunfisk was, it still obeyed Palpitoad, proving it doesn't function well in a group without being a 'follower'. After Cilan caught Stunfisk, its personality did not change; as shown in Archeops In The Modern World! where after being brought out by Emolga's Volt Switch it attacked a newly revived curious Archen with a ThunderShock attack when Archen bit it and subsequently laughed. However, it seems to have completely accepted Cilan as its Trainer, and new leader figure. In Crisis at Chargestone Cave!, Stunfisk did not show any aggression towards the other Pokémon, even smiling as it watched Oshawott flirt with Emolga, showing that it is satisfied with its group.
