Pokemon the Movie 17: Diancie and the Cocoon of Destruction

The movie takes place in Diamond Ore Country, an underground region inhabited by Pokémon Carbink, where Princess Diancie resides. The country's energy source is the Sacred Diamond, which can only be created by Diancie herself. However, Diancie currently lacks the ability to create a new Sacred Diamond, and the existing one's power is dwindling, threatening the country's survival. Diancie joins forces with Ash and Pikachu to find Xerneas, a legendary Pokémon with sacred power, but their search is complicated by Yveltal, a destructive Pokémon said to have ended life in Kalos, who is hiding in a nearby cocoon.