This thing's ability is crazy. Circumstantial, yes, but crazy good if you meet the requirements. Here's a list of all moves it should be able to copy:

Rain Dance (Would fail anyways, I guess.)
Petal Dance
Feather Dance
Dragon Dance
Quiver Dance
Teeter Dance
Swords Dance
Fiery Dance
Lunar Dance

Most of these are stat changing moves, which is fine. But imagine it just copying an attack like Petal Dance and completely destroying the Pokemon who used it. Then again, why would you Petal Dance a flying type? Who knows. Either way, probably my new favorite ability in the game. Every time I see a new Pokemon I want it on my team!… But there's only 6 spots… :c

*Cresselia uses Lunar Dance
*Cresselia an heroes
"Oricorio's Dancer"
*Oricorio uses Lunar Dance
*Oricorio an heroes