Things You'll Need
Instructions
Save your game by pressing "Start," then "Save" then "Yes" before attempting this technique.
Attach the item you want to duplicate to any Pokemon in your party by selecting "Item," then "A," pressing "Hold," then selecting "Pokemon" then "A."
Stand in front of your PC in any Pokemon Center. Turn on the PC by pressing "A" then access Bill's PC by pressing "A" again. Select any empty BOX by pressing "A" again.
Move the Pokemon with the held item to be duplicated into the empty BOX by selecting "Pokemon," pressing "A" then selecting "BOX."
Agree when prompted to save, and wait for the screen to read "DON'T TURN OFF THE POWER." When this occurs, immediately turn off the power before the next line appears. You have about one second to do this.
Turn on the game, and you should be standing in front of the PC again. Your Pokemon with the held item should appear in both your party and the BOX, where it was deposited.