Clone ANY Legendary
Do the first few cloning steps the same as usual.(Put the legendary in, save, turn the GB off, turn the GB on again,take the legendary out.)Then,go to the multi link lady right next to the PC, and even though the lady says your legendary(s) can't be entered, it doesn't matter, you just click on 2 other pokemon.After that, click yes to her first question, and click no to her second question. Turn your GB off, then turn it on again. Check your party, and check your PC. They're both there. Trust me on this. In the summer of 2006 I got a Mew at the
TOYS R US Nintendo Event, and I was able to clone it, so now I have several My friends have been dying for a Mew, so I gave them one. Hope this helps!
Theres loads more info this game, right here, with some cheats and tips, answers and Pokemon Emerald walkthrough.