@Varna, When you say Overpowered, Do you tend to include only Ubers? Or some OU's like Tyranitar, Scizor Ect.?
Don't get me wrong, Overpowered sounds great but you will have to make the messege clear will it only be Ubers or A Mix of Ubers and OU's.
@Illithian: A Private testing is a good idea but for a timed period. After a few weeks of Private testing you could release it to the Community.