1. Go to the Battle Frontier, then enter the Battle Tower.
2. Go over to the PC in the corner of the room. Have any pokemon in your party hold the item you wish to clone(this glitch will clone both the itme and pokemon, so can create multiple legendaries and master balls at the same time).
3. Deposit said pokemon into an EMPTY BOX. No other pokemon can be in the box. Do not 'move' the pokemon into the PC; it will cause the glitch to fail.
4. Exit the PC then save your game.
5. Withdraw your pokemon into your party.
6. Enter the pokemon in a double battle, open level. When asked if you wish to save, say yes. When the screen says it is saving your game, turn off the power.
7. Turn the power back on.
8. Your pokemon will be in your party and in your PC along with the item it is holding.