Before you can do this cheat, you must have 
the Healberry in the top left corner of the 
screen. Then get into a battle and have Rudy 
use a Healberry. Then, have Jack switch 
Healberries with any other item and then defend. 
Have Celia defend. Then have Rudy do the same 
as before. Have Jack put the Healberries back 
and defend. Have Celia defend. Then, you will 
have 255 of the item you switched with the 
Healberry. When you switch the item with the 
Healberry you must have one of the item.