Check out other people's trade threads. Many people offer event pokemon which you can obtain by trading with them.
SoulSilver: Friend Code- 1549 4691 2103 ID No.- 56183
White2: Friend Code- 0734 4129 3640 ID No.- 14741
Time Zone- -5 GMT
Check out my Trade Thread: Fallen's Trade Center Gen4 and Gen5
I sprite a little on my free time, check it out: Fallen's Art Gallery