Mystery House

A new feature in Pokémon Mystery Dungeon Rescue Team DX is the Mystery House. In many dungeons, you'll find a building within the dungeon. This building is normally inaccessible unless you have purchased an Invitation from Kecleon's Shop. If you don't have an invitation, you unfortunately cannot enter

Should you have an Invitation, then you can enter the Mystery House. Within this house, you'll get a variety of items including Reviver Seeds and Max Elixir. In addition to that, if you speak to the Pokémon in the Mystery House, they will be wanting to join your journey. These Pokémon are ones that don't normally appear in the dungeon but will often feature the same theme as the dungeon as it is such as typing. For example, you could find Lapras in Northwind Field as it matches the Water and Ice motif. This is the only way to find Riolu