Pokémon Pokopia’s Bubbly Basin Pokédex includes 50 Pokémon.
Bubbly Basin is the first additional area introduced through the Pokémon Pokopia Expansion Pass. It is an underwater setting based on a submerged Cerulean City, with recognizable features such as Nugget Bridge, Cerulean Cave, Cerulean Gym, and Bill’s House reimagined beneath the sea.
The expansion’s collection is separate from the main Pokopia Pokédex. Players begin building the Bubbly Basin list after entering the area and interacting with Popplio. New underwater habitats then provide the conditions needed to discover and befriend the expansion’s Pokémon.
The number 50 is easy to confuse with 36, which refers to the number of habitats reported for Bubbly Basin. Those figures measure different things: one counts Pokémon entries, while the other counts habitat designs. The area also requires the Dive ability to reach its submerged sections, but Dive is an access mechanic rather than part of the Pokédex total.