Question: pokemon ultra sun and moon how to get lycanroc dusk form?
Answer: Obtain a Rockruff with the Ability Own Tempo (only available via the above giveaway, or breeding Rockruff from that giveaway).
Wait until 5am in-game (note that, in Pokémon Ultra Moon, that's 5pm in real-world time).
Level up Rockruff via any means, between 5pm and 5:59pm.