Another of the brand new features within dungeons is a feature where you will randomly go into another dungeon when you access stairs. This only occurs after the completion of the game and will send you to another area. This change will last for a few floors and when you return to previous dungeon, you will be at the floor equivilant to how many floors you missed. So if you left the dungeon on 3F and were gone for 5 floors, you'd return at 9F. However, the areas vary based on several circumstances including the dungeon you were in as well as the Mystery Level of the dungeon. The higher the level, the better the possibility
The more common of the areas you go to are the mapless dungeons. These dungeons have their own special differences that can manipulate your gameplay somewhat. The possibilities are as follows
The next type of areas you go to are the Mapless Street dungeons. These dungeons lack any kind of floor count and contain a variety of items and Pokémon at random. These are typically determined based upon the Pokémon from the dungeon you entered. However, there is some variation upon that. The Mapless Street is the only way you can receive the other starter Pokémon; Snivy, Tepig, Oshawott, Axew and Pikachu without the use of DLC dungeons. They will appear as follows
The second type of mapless dungeon is the Golden Chamber. This chamber is rare to enter, more likely the higher the Mystery Level. Unlike Mapless Street, it contains random Pokémon and it has rarer items within. There is an extra twist with the Golden Chamber though, it can hold Legendary Pokémon
If you enter the Golden Chamber while in the Quiet Tundra, Dream Island or Moonlight Forest dungeon, you have a chance of finding Tornadus while if you enter through the Iron Rust Mountain, Large Pit or Smokey Mountain dungeon, you may be able to find Thundurus. These Pokémon aren't guaranteed to join you but can be revisited each time you enter the Golden Chamber from these dungeons.