Secret Room

Secret Rooms are a feature that was added to the game in PMU 7. They are areas in dungeons that can be accessed through entering golden stairs found on a dungeon floor. These stairs have a random chance of spawning on a floor and initially spawn hidden. The floors a Secret Room can spawn on and the rate of appearance varies on the dungeon.

Not all dungeons have Secret Rooms, and Secret Rooms can only appear in randomly-generated dungeons. Fixed dungeons such as Friendship Forest will never have Secret Rooms. Secret Room stairs also cannot spawn on the last floor in a dungeon or its given section. Secret Rooms often reward players with a varying amount of Deluxe Boxes that can give items when opened at Xatu's Appraisal. However, some Secret Rooms also allow players to obtain rare, exclusive Pokémon.

Dungeons with Secret Rooms
The following below lists the dungeons that contain Secret Rooms and their corresponding information.

Exbel

 * Island Garden - two boxes
 * Honeydrop Meadow - Scyther (Dawn), Pinsir (Dusk)
 * Far Thunderstorm Forest - two boxes
 * Gritty Burrow - two boxes
 * Mistspring Woods - two boxes and Oricorio
 * Loch Lenile Cavern - Red Moon Spring (11-20F), two boxes
 * Mineral Cavern - one box
 * Mt. Barricade - five boxes
 * Mt. Skylift - two boxes
 * Southern Sea - four boxes
 * Harmonic Tower - three boxes (50-74F), one box and Bagon (75F+)

Winden

 * Winden Forest - two boxes
 * Sauna Cavern - three boxes
 * Crystal Ruins - one box
 * Snowveil Den - two boxes
 * Mt. Stormhold - two boxes
 * Sky Fortress paths - two boxes
 * Sky Fortress Sky Garden - four boxes
 * Concealed Laboratory - Porygon
 * Risen Derelict - two boxes

Tanren

 * Rocky Shoreline - Basculin
 * Mystic Coven - Dusk Lycanroc (31-40F) (Dusk), Midnight Lycanroc (41-49F) (Night)
 * Sunken Gardens - one box, Alomomola
 * Sunrise Temple - Larvesta egg
 * Tanren Graveyard - Mimikyu
 * Tanren Mines - two boxes
 * Tanren Mines Depths - two boxes
 * Tanren Basement - four boxes
 * Tanren Courtyard - two boxes, Spiritomb (Night)
 * Iceberg Cavern - entrance to Iceberg Frigid Waters
 * Iceberg Frigid Waters - Lapras
 * Iceberg Adrift - two boxes
 * Deserted Tomb - two boxes
 * Dynamo Sands - two boxes
 * Daydream Dream Grove - two boxes, Cresselia (31F+)
 * Nightmare Dream Grove - two boxes, Darkrai (31F+)
 * Undercity Catacombs - two boxes, Vullaby
 * Ancient Caustic Sewers - two boxes

Archford

 * Stark Volcanic Woods - Victini
 * Boggy Wastes - four boxes
 * Starlit Lagoon - two boxes and female Meowstic
 * Inferno Volcano - two boxes
 * Seafloor Ruins - two boxes, Phione (Central)
 * Mysterious Jungle - two boxes
 * Mt. Moon - two boxes and Elgyem
 * Sandy Shallows - Alolan Raichu
 * Murky Trench - two boxes
 * Shimmering Seabed - two boxes

Red Moon Spring
The Red Moon Spring is a special Secret Room in Loch Lenile Cavern. The player can regenerate Fossil Pokémon using Fossils when the time of the day is night.