On June 6, it was officially revealed that the next games would be Pokémon Ultra Sun and Pokémon Ultra Moon and that the story would be a different take on the story of their predecessors.
These games differ greatly from Pokémon Sun and Moon, including the following; 100 more pre-existing Pokémon to catch, new ultra beasts, a new form for lycanroc which is launch exclusive, various changes to the region itself, new Poké-ride Pokémon, new forms for the prism Pokémon necrozma, a new evil team, more interactivity with the rotom-dex, more exclusive Z-moves, the return of team Rocket, and the ability to travel to and from various other ultra spaces in which the player may have a chance to catch legendary Pokémon
Pokémon ultra sun and Pokémon ultra moon are to be the final Pokémon games released on the Nintendo 3DS with future titles being released on the Switch, as confirmed in an E3 2017 announcement