Duplicate items
Note: This trick requires a link cable and two Neo-Geo Pocket systems. Save the current game on the "host" system. Link the "host" system to the "guest" system. Trade the item to be duplicated to the "guest" system. Turn off the "host" system. Turn on the "host" system and load the previously saved game. Trade the now duplicated item from the "guest" back to the "host" system.