Equipper
From Inkipedia, the Splatoon wiki
The Equipper is a mechanic in the Octo Expansion.
It is a metallic pad with shoe prints printed on top. Activating the Equipper raises a glass cylinder with rotating metal plates, while a menu is shown with one to three weapon loadouts - sets of main and/or sub weapons, a special weapon, or an unarmed option. Choosing a loadout selects it for the next mission or section.
Upon completing a mission, the player returns to the Equipper, receives the mem cake for the mission, and returns the equipment for the mission, taking the player back into the train.
If the player returns to a previous Equipper of the start of a section, the player is forced to activate the Equipper, and returns the equipment for that section, before proceeding.