The player meets Cresselia, which is actually Darkrai disguised as such, who attempts to eliminate the player and their partner, blaming them for the distortion in space.
All Pokémon in this dungeon are unrecruitable, due to the fact that they are all manifestations of Azurill's nightmare, and not actual Pokémon. Once cleared, the dungeon cannot be returned to outside of friend rescues.
Gameplay
The floors are ranked E, ★1 and ★2, for purpose of Treasure Boxes and friend rescues.
The floors are large-sized, with varying maximum amount of rooms: 10 on floor 1, 11 on floor 2, 8 on floor 3, 13 on floor 4, 17 on floor 5 and 14 on later floors. There's 2-5 items on each floor. There's 2-3 starting enemies on floors 1 through 4, 2-4 on floors 5 through 8, and 3-5 on later floors.
The IQ Booster activates on every even floor. Turn limit is 1000. Items have 5% chance to be sticky. Enemies in floors 1 through 9 have 150IQ, and 331 on later floors. Floors 3, 4, 7, 8, 11, 12, 15 and 16 feature air tiles. There is light darkness in the dungeon.
Pokémon encountered
Each time player enters a floor, only 14 of the species that can be found on a given floor will be chosen. The unpicked Pokémon's spawn rate will be added to whichever picked Pokémon is next in the National Dex order, going back to the beginning if needed.
Several Pokémon encountered in this dungeon are of the same species as the NPCs in Treasure Town and the Wigglytuff Guild (e.g. Wigglytuff, Croagunk, Chansey, Spoink, Spinda, Wynaut, Wobbuffet), and therefore are Pokémon Azurill would already know, hence why they appear in his dreams.
