In the beginning Diancie is playing hide and seek and the little carbinks find her and the royal guards find her and a big pile of crystal falls top of them and princess Diancie starts laughing and the elder comes to see her. Elder starts explaining to her about the heart diamond in her kingdom soon is going to die out, but she didn't believe it and elder told her to make a heart diamond she tries, but it did not come out and elder to her go to Xernas to find her true power, so she goes out into the world to find Xernas and Diancie saw the beautiful sky, trees, and nature for the first time in her life. She was going to find Xernas but a man and women was trying to catch her and she got away from them and went into the city. Ash was in battle Pokemon and the opponent made the Pokemon evolve into mega Pokemon and Ash lost the battle. Team rocket noticed Ash ,Pikachu ,and his friends there in the city and Ash saw Diancie was in trouble from the man and woman trying to catch her . Ash told Diancie to run away ,she did and went with his friends away from there the man and woman in the city. After Ash and his friends got to know Diancie and they decided to go eat and team rocket keep eye on them . Bonnie ,Pikachu ,and Diancie went to get more food ,team rocket caught Diancie and took her took her to the clock tower and ask her to make diamonds and she did after trying to get away from them and a girl helped Diancie to be free and Ash and his friends found dance and decide to go to places to sleep for the night. Diancie couldn't sleep so she tries to make a another heart, diamond, but she couldn't and Ash told her to make a wish on a shooting star. Ash and Diancie made a wish and Ash hope Diancie to make a heart diamond. The next morning they went on a boat and the Pokemon in the water got them wet and started to laugh and Diancie learned the word friend and became friends. Diancie told Ash and his friends about Xernas and she was trying to Xernas to find her true power. Ash and his friends went to the mall ,and she didn't know what was shopping so Bonnie went shopping with Diancie . Diancie was trying clothes on she noticed the royal guard was looking for her and she started running away . Ash noticed Diancie was in trouble, so he caught her and ran away from the mall and find a place to sit ,but when they did the bad women and man tries to get Diancie again Ash fights the women Pokemon and Ash friends fight the man attacking them . The royal guards block the attack from hitting Diancie and got away from the bad people catch her. Soon they were back more into the forest and went to Diancie Kingdom and saw the heart diamond died out . Diancie ,Ash and his friends went to find Xernas they found her and she granted Diancie wish and she was going to try her power that is when the girl with her father capture Diancie and try to take her away and the two other bad people were there too. Ash and he fought them and soon they accidentally woke up the Yveltal cocoon of destruction and start killing everything and turning into stone. Soon everybody was running for their lives and try to get away from Yveltal . Pokemon was turning into stones and then the man and women into stones and team rocket was also into stones .Ash and his friends fought hard to get away from Yveltal and Xernas saw Yveltal aurora and start going to the forest he was killing Pokemon and trees. Xernas saw what is happening and stop him attacking went back to sleep and soon started to bring life to forest and Pokemon. Xernas planted herself to forest so that Yveltal not be awake again .Dance made heart diamond and the kingdom was back to life and they remember each other in the rest of their lives and had a happy ending for the movie.