The game focuses on performing research in the Hisui region. The Hisui region is the Sinnoh region in the past. Players will continue to catch Pokémon and battle with them. Players can capture wild Pokémon in the overworld without engaging in battle, though some must still be battled before being caught. Battles can be initiated by releasing captured Pokémon near a wild Pokémon. New Alpha Pokémon will appear are stronger than the normal counterparts. Alpha Pokémon can be spotted by their glowing red eyes. The player is able to roam freely across the game map that is divided into five large areas of individual regions.
In this game, the player character themselves can be attacked and harmed by wild Pokémon. If enough damage is taken, he or she will fall unconscious and will be rescued and taken back to the base camp.
Upon released, the game featured 242 Pokémon and featured new variants such as Hisuian Voltorb and Growlithe. Other Pokémon received new evolutions such as Wyrdeer (from Stantler) and Basculegion (from Basculin).
The game received favorable reviews. It was praised for its creativity, graphics, and the freedom to explore. Nintendo reported the game had sold 6.5 million copies in its first week of release.