The August Issue of CoroCoro has begun to leak, and new details on Dusk Form Lycanroc have been revealed.
The new form has access to both Accelerock and Counter, moves heavily associated with the Midday and Midnight Forms respectively, and has the ability Tough Claws. It is a pure Rock-type.
As well as this, a "special Rockruff" that will evolve into Dusk Form Lycanroc will be distributed to copies of Pokémon Ultra Sun and Pokémon Ultra Moon from November 17th, 2017 to January 10th, 2018.
The magazine states that special distributions are the only way to obtain this form in the upcoming games.