In the post story.
in azurills nightmare. darkrai is the one causing the nightmare and is the boss of this dungeon.
They don't have it in Explorers of Darkness, only in Explorers of Sky
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The Nightmare has 17 floors.
When you finish the game and you graduate from the guild and a bit later Azurill will have a nightmare and you have too get Drowzee, a Pokemon will tell you where he is and he will send you to the nightmare.
You Can't
its marine resort
yes it is
Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness will be released in Europe on the 4th of July, 2008.
You can't explorer the nightmare again, but you can visit Palkia at Spacial Rift and I'm pretty sure that he has a 100% recruit rate!!! I got him on my first try!!!!!!!!!
The Temporal Tower has 23 floors in "Pokémon Mystery Dungeon Explorers of Darkness."
Have you fainted in a dungeon yet?