Darkrai Cult Base

In the side of a fortified hill is a metal door. Beyond the door is a seemingly abandoned house, but in truth this is only a disguise placed by some not-so-friendly ghosts. Through the entrance hall is a complex devoted to the worship of the Legendary Pokémon Darkrai, now mostly inhabited by Hypno and Drowzee. Some Houndoom patrol the halls, and Golett still follow their old instructions to maintain and operate the facilities.
In the depths of the cult base is a ceremonial room with seven funnels arrayed in the walls and a grate embedded in the floor. The connection to the dream is strongest in this room, and those with weaker mentalities or already existing connections may find themselves passing out as soon as they enter.
Recently a Musharna has moved in and is using its psychic powers to create illusions. It is using this ability to drive off intruders, so the Pokémon already living there don't really mind.
The base was abandoned by the cultists when two of their number preformed a forbidden ritual and sealed their god away.

Defences

The base is trapped, with special security bronzong that hold the doors shut.

Assets

The cultists had a large stockpile of weapons, a training facility, and enough living space and supplies to remain in the bunker for years.