From Bulbapedia, the community-driven Pokémon encyclopedia.
The partner asking to help make Pokémon Paradise
Pokémon Paradise is an outside-of-dungeon place near Post Town in Pokémon Mystery Dungeon: Gates to Infinity, established by the partner Pokémon.
The location becomes accessible after completing the first dungeon. Initially, it only contains the Passerby Post where the player can deposit Reviver Seeds which saves other fainted players through StreetPass instead of manually rescuing them like in previous games. This is also where all your recruited Pokémon stay. As the story progresses, the player will be able to expand land, play mini-games, rank up and place custom stores.