Our Trade Corner and Battle Center sections might be just the place for you! They have some good topics in there relating to trading and battling respectively. The former has a cool chatroom, the Quick Trade Thread and the awesome Trade Shops in there while the latter also has a section where you can post Rate My Team threads and get team advice as well.
We also have a Pokemon Showdown server you can check out. I'm over there as +OshyHikari so feel free to pop by anytime!