In Pokemon Sun and Moon, players get to explore the brand new Alola Region, which is comprised of four natural islands and one artificial island.
Each of these four natural islands; Melemele Island, Akala Island, Ula’ula Island and Poni Island, also have their own guardian deities. These are Tapu Koko, Tapu Lele, Tapu Bulu, and Tapu Fini respectively, and the player can catch and add them to their own roster of Pokemon. This guide will show you how and where to catch each of them.
To get Tapu Koko, just play through the game until you defeat the Elite Four. After a brief sequence celebrating your victory, Lillie will lead you to Tapu Koko’s altar at which point you will engage it in a battle. Make sure to prepare for this encounter before challenging the Elite Four, as there is no gap between these two battles.
Head to Akala Island and go to the Temple of Life past the Memorial Hill. Use Machamp Shove once inside to push the right-most box up into the hole. Now push the box directly to the left into the left hole, and then push the box on the left side in front of you up into the hole. You now get to battle Tapu Lele.
Head to Ula’Ula Island and go to the Haina Desert. Now head north, then exit to the east, and then north again. Now use Mudsdale Gallop to traverse the obstacle in front of you and then keep on going north to reach the Ruins of Abundance. Now just solve a very simple puzzle using Machamp Shove, and the door should open to Tapu Bulu.
Head to Poni Island and go to the Ruins of Hope, which should already have been solved from the events of the main game. Just go right on ahead and battle Tapu Fini.
Hopefully this guide was helpful in catching these four Guardian Deity Pokemon.