An Appetite for Battle! (Japanese: ハリマロンVSマフォクシー！ダイエットバトル！？,Chespin VS Delphox! A Diet Battle!?) is the 15th episode of Pokémon the Series: XY.
Chespin gets fat after eating so many of Serena's macarons, so Clemont decides to put it on a diet by making an exercise machine and having it exercise through Pokémon Battles, but Chespin is not making progress.
Continuing their journey, our heros decide to camp out. Serena reveals that she has not prepared her camping gear despite of her mom telling her to do so. Clemont offers that she could use his extra sleeping bag and Bonnie tells her that she could sleep in her tent which Serena accepts. After having lunch Serena offers macarons to everyone. To their surprise Clemont's Chespin ate all the desert leaving everyone sad. Ash decides to have a battle and chooses Froakie against Chespin. Ash easily wins as chespin overate and was very slow. Bonnie and Dedenne challenge Clemont and Bonnie easily wins embarassing Clemont and his gym leader pride. At night Clemont is making an exercise machine for Chespin and then he puts it on to try it. Meanwhile Chespin sniffs a tasty aroma and gets attaracted towards it. The machine explodes waking everyone up and they discover that Chespin is missing. They all search for him. On the other hand Chespin is lying outside a house where macrons are prepared. An old lady picks him up and takes him inside. Clemont blames himself as he thinks that Chespin ran away. Chespin wakes up and is delighted to see the macarons. The lady offers him macarons.When Clemont comes looking for his wayward Pokémon, he sees Chespin happily munching macarons with Carrie on the porch and decides Chespin is better off right where it is. Will chespin ever reunite with Clemont? And who is Wylie? And who is delphox? why are delphox and Chespin battling?