Ash, Clemont and Bonnie first encountered Dedenne in A Battle of Aerial Mobility during their journey to Santalune City. Bonnie was eager to care for the cute Pokémon, and asked Clemont if he would catch it for her to allow her to raise and take with her when she was old enough to be a Pokémon Trainer. Clemont agreed, and Ash helped her; however, Dedenne ran off crying when a Fletchling stole the berry it had harvested from the tree. After the same Fletchling was captured by Ash, Dedenne was last seen watching the group as they leave.
Soon after, in A Shockingly Cheeky Friendship!, Dedenne reappeared to the group and stole some food and the gang gave chase. This resulted in Pikachu getting lost alongside Dedenne. The two became friends, and managed to save each other from Team Rocket. After reuniting with the group and defeating Team Rocket, Clemont captured Dedenne and then allowed it out of its Poké Ball so it could stay with Bonnie in her satchel.
In An Appetite for Battle!, Bonnie used it in a battle against Clemont's Chespin. Due to Chespin being overweight at the time, it tripped during its attack, falling near Dedenne where a single Thunder Shock defeated the Grass type, giving it and Bonnie the win.
In A Jolting Switcheroo!, while the group was resting at a Pokémon Center, Lyn took Bonnie's bag, mistaking it for her own since the two bags looked so similar. Since it was resting inside earlier, Dedenne was accidentally taken by Lyn and her older sister Lena. When it woke up, it accompanied Lyn while she tried to find her Pichu. Lyn also gave it a ribbon, which was used for identification when she lost Dedenne. When Clemont used his "Radiowave Amplification Device" to amplify Pikachu's energy waves, Dedenne found them and began to follow them to a vineyard where they were both attacked byBeedrill. Though it fought off one of the Beedrill with Thunder Shock, it was attacked by several more. Eventually, it was saved by Pikachu and reunited with Bonnie. It later had dinner with Ash, his friends, Lyn and Lena but it was not hungry as it was given lots of snacks by Lyn during the day.
In One for the Goomy!, Dedenne tried to be friendly to Ash's Goomy, but it was afraid of Dedenne as Goomy, a Dragon-type, was weak against Fairy-typePokémon. Team Rocket showed up and attempted to capture everyone's Pokémon, and were attacked by startled Lotad and Lombre, and Dedenne was separated along with Goomy, Pancham, Serena, and Bonnie. Dedenne tried to give Goomy leaves on the way to help regain its energy but it was still scared. Later when Serena was battling Team Rocket with Pancham, it used Nuzzle on Pancham after it got confused and, under Bonnie's command, teamed up with Pancham to defeat Team Rocket. Afterwards it followed Goomy's slimy trail after it ran away, due to the battle reminding it how its original home was destroyed by Bug-type Pokémon. It traveled through a small hole to reach Goomy, who was about to be captured by Team Rocket. It battled them again, but was almost defeated until Goomy, who saw that Dedenne was trying to help it, used Rain Dance, distracting them long enough for Ash and friends to find them, leading to Team Rocket being defeated once more. Overcoming its fear of Dedenne, Goomy affectionately nibbled on Dedenne's ear, which made Dedenne happy.
Despite officially belonging to Clemont, in The Future Is Now, Thanks to Determination!, Dedenne stayed with Bonnie when Clemont left for Lumiose City
It was made clear in its very first appearance that Dedenne is a gluttonous Pokémon. In A Battle of Aerial Mobility!, its desire for a berry was strong enough that it was willing to fight Pikachu over it, and it only approached Bonnie because she had the berry in her hand. It reappeared to the group in A Shockingly Cheeky Friendship! to steal food. Dedenne is also a bit timid, as shown in its debut when it got scared off by Fletchling swooping in. In A Shockingly Cheeky Friendship!, although initially unresponsive to him, Dedenne becomes very close to Bonnie, as it is often seen in either her hair or satchel. Dedenne is also prone to sleep while it is conserving its electrical energy, although it does so at the most inconvenient times, such as when it slept during attacks by Team Rocket in Grooming Furfrou! and Mega-Mega Meowth Madness!. However, Dedenne has been shown to be a competent battler when it is focused, and has no problem taking commands from either its Trainer or carer. Dedenne can sometimes be an affectionate Pokémon as shown in A Shockingly Cheeky Friendship! and Going For the Gold!, when Bonnie nuzzles Dedenne, she causes it to use Nuzzle, giving Bonnie a shock. In Bonnie for the Defense! andOne for the Goomy!, it has been shown to be affectionate to others as well.
Dedenne has special relationships with a few specific Pokémon. In particular, it has a sibling-like relationship with Ash's Pikachu, looking up to and respecting him. The two of them often communicate using the electrical energy from their cheeks, such as in One for the Goomy!. Ever since that episode, Dedenne has also had a remarkably strong friendship with Ash's Goodra. Although the latter was frightened of Dedenne at first, they became friends once Goodra, as a Goomy, realized how much Dedenne cared about it and was willing to go to any lengths to keep it from harm. Their bond was also shown in Good Friends, Great Training!, when Dedenne gave Sliggoo a hug after they were reunited, Defending the Homeland!, when Goodra shared its food with Dedenne, and Beyond the Rainbow!, when the two of them had to say goodbye to each other.
- Dedenne is the first recurring Pokémon to be caught by a main character other than Ash.
- Dedenne is the first walking Pokémon in the main cast to be traditionally captured in the wild by its Trainer.
- Dedenne is the first Fairy-type Pokémon to be caught by a main character. This excludes all previous Pokémon of this type that were owned by main characters before Generation VI, those being Misty's Togetic and Azurill, Tracey's Marill, James's Mime Jr., and Dawn's Togekiss.