Further details on the new Dusk form of Lycanroc have been officially revealed. It keeps its pure Rock type, and its ability is Tough Claws as we mentioned previously. Its eyes are green but glow red when attacking.
However, a normal Rockruff found during normal gameplay cannot evolve into Lycanroc Dusk form. Rather, only a special Rockruff obtained from an event will do so. This can be obtained via Nintendo Network from the games' launch on November 17th and runs until January 10th 2018.
Lycanroc Dusk Form official artwork