The Pokemon Company has shared a mysterious new video showing off Legendary Pokemons from a variety of their past titles.

From a translation by AwesomePahsome on Reddit (Link):

Pokémon Mystery File

Subtitles
A world of Pokémon you don’t know
Is this a time slip? Is it manipulating time? It came from the moon? Is it a space virus? Is this an encounter with aliens?

Dialog
Thank you. With the power it has received from your Solrock it looks like it can return home… to the sky! Is this a UFO appearance? Is this an alien invasion?

Commentary
The battle with the alien invader has begun! Is this the underside of this world? Is this a puzzle of ancient relics? Is this an attack from a parallel universe? Is it possessing humans?

Written in Unown
Is something happening?

As for right now we can only speculate what The Pokemon Company’s intentions are, whether or not it has anything to do with the upcoming Pokemon Ultra Sun/Ultra Moon games or if it is something brand new.