We heard that Necrozma would be getting new forms in Pokémon Ultra Sun and Ultra Moon; its Solgaleo-looking Dusk Mane form and Lunala-like Dawn Wings form, but we had not received official confirmation of Necrozma’s typing to go along.
Now, with the release of information for its upcoming toy, it seems to confirm that the third legendary will retain the same typing of the Pokémon whose power it is possessing. Dusk Mane Necrozma will be Psychic/Steel, while Dawn Wings Necrozma will be Psychic/Ghost.
Update: I’m also adding a translation of the “secret” revealed for each form, since I know some readers may be curious about what the Japanese says 🙂
Dusk Mane Necrozma’s Secret: It’s claws have been powered up and can tear apart foes. They possess more power than Solgaleo’s and have overwhelming destructive power.
Dawn Wings Necrozma’s Secret: The black prisms on its wings emit a dark energy. It is even more powerful than Lunala!