ROTOM's Room

Rotom's Room is a hidden room in the Pokémon games that appears in Pokémon Platinum, HeartGold and SoulSilver, and Brilliant Diamond and Shining Pearl. It houses five appliances that Rotom can inhabit and thus change forms. If the player interacts with an appliance with more than one Rotom in their party, the game will ask which Rotom the player wants to possess the appliance. Only one Rotom can possess each appliance from this room at a time, thus restricting the player to only owning one of each Rotom form at a time in Generation IV, as Rotom's alternate forms cannot be traded in these games. However, in Brilliant Diamond and Shining Pearl, Rotom's alternate forms can be traded, and the player may obtain the Rotom Catalog here, allowing them to circumvent this issue themselves.