And now that this is where it belongs, I will close it because it should be asked in Simple Questions. Any time you have a question concerning to a Pokemon game, go to its proper forum and ask it in the Simple Questions thread. They are always near the top of the thread listing.
But I want to make sure your question is answered so here you go:
PURIFYING SHADOW LUGIA(Straight from our FAQ)
Yes, most of us all yearn to purify this thing. If you haven't read the info above, do so now.
Step 1: Place lugia in a set.
Step 2: Create a Best Circle in that set.
Step 3: Create a Best Circle in the other 8 sets.
The Shadow Lugia's Heart Guage will instantly turn completely white. Now complete the Purification Ceremony and you'll have a Regular Lugia with Aeroblast, Psycho Boost, Featherdance, and Earthquake.
Sounds simple, but the process requires multiple Shadow Pokemon to be purified, or for multiple Regular Pokemon traded over, so the process will start out slow, then quicken over time.
CLOSED