Like all Pokemon Games, there are certain Pokemon that can only be found In Pokemon Ultra Moon and not in Pokemon Ultra Sun. On the contrary, there are also specific Pokemon that cannot be found in Pokemon Ultra Moon, only being able to be caught and obtained in Pokemon Ultra Sun. Version Exclusive Pokemon can only be obtained in counterpart games via Trade.
Pokemon That CAN ONLY Be Found In Pokemon Ultra Moon
Alolan Raticate (Totem Sized Form Only), Alolan Sandshrew, Alolan Sandslash, Kabuto (Fossil), Kabutops (Fossil), Entei, Lugia, Electrike, Manectric, Baltoy, Claydol, Lileep (Fossil), Cradily (Fossil), Latias, Kyogre, Shieldon (Fossil), Bastiodon (Fossil), Palkia, Regigigas, Petilil, Lilligant, Basculin (Blue-Stripe Form), Archen (Fossil), Archeops (Fossil), Vullaby, Mandibuzz, Thundurus, Zekrom, Skrelp, Dragalge, Amaura (Fossil), Aurorus (Fossil), Yveltal, Araquanid (Totem Sized Form Only), Salazzle (Totem Sized Form Only), Oranguru, Togedemaru (Totem Sized Form Only), Drampa, Kommo-o (Totem Sized Form Only), Lunala, Pheromosa, Celesteela, Stakataka
Pokemon That CANNOT Be Found In Pokemon Ultra Moon
Alolan Vulpix, Alolan Ninetails, Alolan Marowak (Totem Sized Form Only), Omanyte (Fossil), Omastar (Fossil), Houndour, Houndoom, Raikou, Ho-Oh, Anorith, Armaldo, Latios, Groudon, Cranidos (Fossil), Rampardos (Fossil), Dialga, Heatran, Cottonee, Whimsicott, Basculin (Red-Stripe Form), Tirtouga (Fossil), Carracosta (Fossil), Golett, Golurk, Rufflet, Braviary, Tornadus, Reshiram, Clauncher, Clawitzer, Tyrun (Fossil), Tyrantrum (Fossil), Xerneas, Gumshoos (Totem Sized Form Only), Vikavolt (Totem Sized Form Only), Ribombee (Totem Sized Form Only), Lurantis (Totem Sized Form Only), Turtonator, Passimian, Solgaleo, Buzzwole, Kartana, Blacephalon