The Bubbly Basin DLC for Pokopia has expanded its Pokédex with a new collection of Pokémon, primarily focusing on aquatic and water-based creatures. Players can now discover and interact with these Pokémon in a variety of new habitats scattered throughout the Bubbly Basin area.

The new additions range from familiar Pokémon like Shellder and its evolution Cloyster, found in scrub and tall grass areas, to a variety of water-dwellers. Horsea, Seadra, and Kingdra populate coral congregations and specific marine-themed locations, while Staryu and Starmie utilize teleportation abilities in areas such as the Mermaid's Gym. The starter Pokémon Totodile, Croconaw, and Feraligatr are also present, with their respective abilities like Chop and Crush usable in diverse environments including chimney rock dig sites and basin tall grass.

Chinchou and Lanturn are found in a 'Nostalgia zone,' utilizing their 'Generate' ability. Corsola and its evolutions Mudkip, Marshtomp, and Swampert inhabit grassy areas, coral, and muddy zones, with Swampert capable of 'Build' and 'Bulldoze' actions. The aggressive Carvanha and Sharpedo, known for 'Chop' and 'Crush,' are located near seaweed and chimney rocks. Barboach and Whishcash can be found searching and bulldozing through ocean rest spots and muddy areas.

Further aquatic Pokémon include Corphish and Crawdaunt, capable of 'Build' and 'Crush' in sandy habitats. Luvdisc and Buizel are associated with sparkling jewels and smoothie-making spots respectively. Finneon and Lumineon, described with 'Hype,' are found in marine mossy spots and swaying flower beds. Frillish and Jellicent, with 'Search' and 'Burn' abilities, inhabit areas described as 'Ocean treasures' and 'Maritime teatime.' Alomomola can be found in similar oceanic locations using 'Water' and 'Scrub' abilities.

Newer additions like Stunfisk, Inkay, and Malamar introduce unique mechanics such as 'Generate,' 'Teleport,' and 'Gather,' appearing in grassy, muddy, and topsy-turvy environments. Popplio, Brionne, and Primarina, notable for their 'Hype' and 'Trade' abilities, perform in bubbly stages and elegant concert settings. Mareanie and Toxapex, with 'Recycle' and 'Build' actions, are found near treasure chests and coral. Wimpod and Golisopod also utilize 'Recycle' and 'Chop' in discarded treasure areas.

More unique Pokémon include Bruxish and Dhelmise, featuring 'Gather,' 'Teleport,' 'Grow,' and 'Litter' abilities, found in molten and sailor-themed locations. Chewtle and Drednaw are associated with smoothie-making spots and canoe docks, with Drednaw capable of 'Crush' and 'Bulldoze.' Pincurchin generates in creepy chimney rocks, while Wiglett and Wugtrio use 'Bulldoze' and 'Search' in sandy environments. Veluza and Phione can be found in marine mossy rest spots, with Phione's location noted as 'Dream Island.' The legendary Manaphy, requiring a completed DLC story, is also available with 'Trade' and 'Hype' abilities.