Yes, from Smogon:
1. put something with anything attached into the GTS, make your offer ridiculous (Lv9- dialga).
2. Count the number of turns of the clock you see in the bottom-right corner it takes for your game to say "***** will be put up for trade"
3. Take it back out. REMEMBER the exact turns and where it stopped.
4. Put it back in, and two movements before what it took last time for the pokemon to be transferred to GTS, shut it off.
5. Check the box where you chose the pokemon for trade. It should still be there, BUT there is also the clone which is 'still up for trade'
that clear?
Trust me, it works, I've cloned Pokémon with it. You WILL get a blue error screen if it works, the game is just calling up a backup save.