Monster House

Monster Houses, called "MH" for short by players, are special floors that appear at random in most dungeons (barring many in Exbel as they are typically beginner dungeons). Monster Houses are characterized by being one medium-sized room with 20 Pokémon that will usually be encountered on that floor, still spawning in more as normal. Pokémon defeated in a Monster House will yield 1.5x the normal amount of experience.

When encountering a Monster House, a text box saying "It's a Monster House!" appears before any action can be made. Monster Houses can only appear in randomly generated dungeons, on Floor 6 and up. The stairs will always spawn in the bottom-right corner of a Monster House. Traps, Secret Rooms, and tiles such as water will never show up in them, and items in the dungeon that can or will spawn on tiles other than the ground will always be on the ground.

Zorua
Monster Houses are the only place Zorua will spawn, and it will not spawn on its own; a Pokémon with the move Sweet Scent is required. Zorua will only have a chance of spawning with the use of Sweet Scent, so bringing PP restoring items is a good idea. Due to Illusion, Zorua will appear as a random Pokémon on the floor if there are any, otherwise it will appear as a Zorua. Once Zorua is recruited, it will know the moves Sludge Bomb, Punishment, Sucker Punch and Nasty Plot, based on the four Event moves Zoroark can obtain. Zorua can not spawn with the use of Honey.

Trivia

 * Zorua was previously event only.
 * Zorua is the only Pokémon that can be encountered solely through Monster Houses, discounting seasonal events.
 * Pebble Cave used to be able to have Monster Houses upon release, which has since been removed.