Save first before you start. First access your PC. Then put in the pokemon you want to duplicate from your party to Box 8 (it should be alone!) Next, release that pokemon (Don't worry you won't lose it). Then save (it should say Saving a lot of data), turn off the power after 10 seconds (exactly 15 seconds) during the save. Then you should have the pokemon in your party and in your PC box 8.