Pokémon Pokopia's Bubbly Basin DLC centers on rebuilding an underwater town that humans abandoned, and several outlets have published guides breaking down its systems. According to Polygon, six treasure maps are scattered across Bubbly Basin and can be found by digging daily glowing spots on the ground, though players don't need the maps themselves to reach the treasures, which can be found by heading directly to their locations. Each map corresponds to a decorative Poké Ball — Great, Heal, Dive, Net, Lure, and Quick Balls — hidden behind destructible rock or dirt walls near landmarks such as the bathing house, the ocean temple, the abandoned gym, a cave, and a house with a yellow mailbox near the portal pods.
Collecting all six decorative balls lets players build the 'mermaid's gym' habitat, which is Starmie's home, according to Polygon. The habitat requires a marine sofa, six pedestal or exhibition stands, and one of each decorative ball. Polygon notes that six exhibition stands can be found inside the abandoned gym tied to Treasure Map #3, making that location a shortcut for assembling most of the habitat once all six balls are collected.
The main Bubbly Basin storyline revolves around the 'Build the Beautiful Building!' request, in which Popplio asks players to construct an ocean temple. Polygon's walkthrough describes clearing sand and grass from the building site, completing side requests for Corphish, Corsola, Mareanie, Totodile, Frillish, and Barboach, and gathering Pokémon and materials — including ocean doors, seashell fencing, star-spotted rocks, stones, seashells, and shiny pearls — before depositing them at the temple and waiting an hour for construction to finish. GamesRadar+ adds that completing this storyline, which requires reaching environment level 3 and finishing the temple, causes the Mythical Pokémon Manaphy to move into Bubbly Basin permanently; Manaphy has no dedicated habitat to build, unlike other Pokémon, though GamesRadar+ notes this could change in the future.
Additional Polygon guides point to other collectibles tied to Bubbly Basin habitats. A windup Inkay doll can be found for free in a cave behind the pavilion where players retrieve Barboach's seashell seat, reached by following a road into the ocean depths, through a tunnel, and past rocks breakable with Rock Smash; the item is needed for the Muddy Playtime habitat. GamesRadar+ separately details the Ocean Pals rug, requested by Stunfisk, which is found inside a hidden, partly sunken house in the northwest corner of Bubbly Basin, and notes a similar Swampert Squad rug found nearby that no Pokémon has yet requested.
GamesRadar+ also published crafting guides relevant to the DLC. Its flavor guide explains that Pokémon request specific taste categories — neutral, bitter, dry, sweet, sour, or spicy — matched to certain berries, vegetables, and ingredients, including DLC additions like watermelon and sea grapes, and that offering flavored dishes to Mosslax's shrine grants daily bonuses such as increased Lugia and Ho-Oh sightings or better shop stock. Separately, GamesRadar+'s paint guide explains that black and white paint, unlike other colors, don't come from a specific berry but instead have a chance of appearing as a bonus whenever Pokémon with the Crush Specialty produce other paint colors from crushed berries.
Alongside the guides, a Polygon opinion piece compares the labor required to build Popplio's temple unfavorably to Palworld, noting that gathering the necessary materials takes a long time and that, unlike Palworld's Pals — which the piece says divide tasks like farming, mining, and construction — the Pokémon in Bubbly Basin largely do not help with the gathering work, leaving the player to do it alone while the writer estimated the site-clearing portion of the task took about seven minutes for half the area, with the full process expected to take roughly 15 minutes.