It has the ability to alter the composition of it's body to suit it's surrounding environment.

Aqua: When they say that they mean evolve right?

Amber: Basically yeah. They could do better than that but whatever

Blossom: Oooo I wonder what's my pokedex entry!

Luna: Mine too!

Aqua: You'll get to see it soon I promise or a creepy one

Amber: Which creepy one? The gardevoir one?

Aqua: Maybe or maybe not