Question: is tapu koko a ultra beast?
Answer: Aside from the story required Solgaleo and Lunala the rarest Pokémon include Magearna, Zygarde, the guardians Tapu Koko, Tapu Lel, Tapu Bulu, and Tapu Fini. The Ultra Beasts include Nihelogo, Phermosa, Buzzwole, Xurkitree, Celesteela, Kartana, and Guzzlord.