A Trawl Orb is required for this trick. Occasionally you will find a Kecleon shop in a dungeon. If you drop an item on his carpet and step off, he will give you money for that item. Drop anything you can on the mat, except the Trawl Orb, and leave. Then, locate the room with the stairs and use the Trawl Orb. All unclaimed items on the floor will be transported to that room, including Kecleon's items and the items you dropped on his mat. Immediately pick them up and enter the next floor. Note: Kecleon will either call all the Pokemon on that floor to attack or summon other Kecleon's to fight you. Do not fight them since they have a good chance at a one hit kill. Thus, use the orb in the same room as the stairs.