The fastest way to farm Fluff
Fluff isn't mined or grown — it's a passive Litter drop from Wool Pokémon like Mareep, Flaaffy, and Wooloo, all findable on Bleak Beach.
Fluff comes exclusively from the Litter specialty, which certain Pokémon express by periodically dropping items around their own habitat rather than handing them over directly. Mareep, its evolution Flaaffy, and Wooloo all carry this specialty and all appear on Bleak Beach (unlocked via the "Yawn Up a Storm" request), so building even one of their habitats there gives you a standing Fluff source.
Fluff balls spawn around the habitat periodically rather than all at once, so the efficient loop is to sweep a habitat clean, leave the area to do something else, and circle back later to collect whatever has respawned — camping in place doesn't speed up the respawn timer. Building a second habitat for the same species elsewhere adds a separate spawn point if you want to double up.
Related: Fluff
Regions: Bleak Beach