In black 2 and white 2 there was an item called "Dropped Item" that could be found in Nimbasa City fair grounds. After picking up the item and stepping in 10 specific tiles a person called Yancy/Curtis (depending on gender) would call the player on an x transiever. After stepping on all the tiles Yancy/Curtis would invite the player to ride the ferris wheel with them. After the ride Yancy/Curtis will offer to trade with the player. Yancy/Curtis offers a cranidos with hidden ability in exchange for any Pokemon.