Diancie

Diancie is a dual-type Rock/Fairy Pokemon. It was leaked along with Volcanion and Hoopa on Serebii.Net but wasn't revealed as an actual Pokemon until much later. Diancie appeared in the 17th Pokemon film alongside Xerneas and Yveltal. It can Mega-Evolve.

Biology
Diancie is a gray, sylph-like Pokémon with a white chest and arms resembling a dress. Its headdress consists of pink crystals, four short ones cresting along top pointing upward and two long ones on either side of its head pointing downward, with a diamond-cut centerpiece framed by its slim gray ears. A smaller pink crystal is also embedded in the back of its head and a gold nugget is embedded in its forehead. Its eyes are red with pink irises. A gold crescent circles its neck, with the ends joined by a rhomboid gem. Its lower body resembles a large oblong chunk of stone, with a large pink crystal protruding from it.

Special Abilities
Diancie is born from a Carbink that undergoes a mutation. It can instantly create diamonds by compressing the carbon in the air; these diamonds can then be used to defend itself.

Trivia

 * Diancie is the only Pokemon introduced in Generation VI to be capable of Mega-Evolution.