Also might be worth noting, I have shiny versions of all the Legendary Pokémon from the Ultra Space Wilds (and the Poni grove beasts) in USUM.
Ultra Sun Exclusives:
Raikou, Ho-oh, Latios, Groudon, Dialga, Heatran, Tornadus, Reshiram, Xerneas, Buzzwole, Kartana, Blacephalon
Ultra Moon Exclusives:
Entei, Lugia, Latias, Kyogre, Palkia, Regigigas, Thundurus, Zekrom, Yveltal, Pheromosa, Celesteela, Stakataka
Not Version Exclusives:
Nihilego, Xurkitree, Guzzlord, Articuno, Zapdos, Moltres, Suicune, Mewtwo, Regi Trio, Rayquaza, Lake Trio, Giratina, Cresselia, Swords of Justice Trio, Landorus, Kyurem