Mesprit is in the underground lake.
Quicksand Cave.
at the underground lake at quicksand cave
A dungeon is a cave on pokemon mystery dungeon. It is a level with a series of floors/rooms and the object is to get to the end of the dungeon.
In Aegis Cave
In solar cave
There are loads in western cave.
entei
Beat Jirachi
Crystal Cave has 12 floors in Pokemon Mystery Dungeon: Explorers of Darkness.
There are 19 floors in the Landslide Cave dungeon in Pokemon Mystery Dungeon: Explorers of Darkness. The dungeon is known for its rocky terrain and challenging battles with ground-type Pokemon.
30
In solar cave you get there after you beat rayquaza