A princess who can't do the one thing her kingdom needs her to do is trapped in a story that actually cares about that weight. Diancie isn't waiting around for the hero to save her, she's running toward her own power, terrified the whole way. The movie understands that desperation and determination aren't the same thing, and it doesn't let either one off easy.
Beneath the earth lies Diamond Ore Country, a hidden kingdom where Carbink live in harmony and Diancie rules as princess. The realm's survival depends on a single resource: the Sacred Diamond, a massive gem that only the reigning monarch can create. But Diancie hasn't mastered this crucial ability yet, and the current diamond is failing. Without a replacement, her entire civilization faces extinction. When Diancie encounters Ash and Pikachu, she convinces them to join her desperate quest. Together they hunt for Xerneas, a legendary Pokémon whose ancient power might save her people. Their journey grows perilous when they discover something far more sinister stirring in the depths: Yveltal, the Destruction Pokémon, rests dormant in a cocoon nearby. This creature once ravaged the Kalos region with catastrophic force, and it's beginning to awaken. Diancie must confront whether her own potential can match the threat bearing down on everyone she loves, while Ash faces an enemy unlike anything he's battled before.