You need a Trawl Orb for this trick. Once in awhile, you will find a Kecleon shop in a dungeon. When you drop an item on his carpet and step off, he will give you money for that item. Drop whatever you can on the mat, except the Trawl Orb, and leave. You will get money for it. 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. Quickly pick them up and enter the next floor. Note: Kecleon will either call all the Pokemon on that floor after your characters or summon other Kecleon's to fight you. Do not fight them. They had a good chance at a one hit kill. Hence, use the orb in the same room as the stairs.