Umbreon can learn Sychronoise, which is Psychic-type. Synchronoise damages Pokemon of the same type as the user, but Dark Pokemon are immune to Psychic moves. If an Umbreon uses Synchronoise on a Dark Pokemon, will it hit?
>Due to the nature of this move, and the Dark type's immunity to the Psychic type, pure Dark-type Pokémon cannot use this move successfully under normal circumstances. ~ Bulbapedia
Synchronoise will fail if used by Umbreon onto a Dark-type.