I don't mean cloning on the GTS, I mean this method : 1. Put the Pokemon you want to clone into your Party, from the BOX. If you already have it in the party, put them into the BOX, save, and take the Pokemon out.
2. Save your game. Then, when you boot up your DS (Lite), change the hour by an amount (30 Min, 60 Min, so on).
3. Reload the Pokemon Diamond/Pearl save.
4. The team should be of the current save file, but the BOX should be of the previous file.
Does that include any dangers?
I do not know any other ways of how, myself, can clone.