Teleporter

From the Super Mario Wiki

In the game Paper Mario: The Thousand-Year Door, the Teleporter is found in the X-Naut Headquarters and leads to a secretly located room in Rogueport Sewers, which the player can use to go back to X-Naut Headquarters since the room is locked from the outside. It was used by Sir Grodus, Lord Crump and the entire X-Naut Legion to transport themselves to Rogueport and back to their fortress on The Moon.

After defeating the X-Nauts, Mario made use of the device to make return trips to The Moon.