Check Marriland (currently down) or Serebii forums. They have some guides. The guides talk about team building and tells the many different battle roles, such as sweepers, tanks, and walls. This site has something like that too, well, just the battle roles - but still, it's a good way to start.
Or you can just watch videos of recorded matches.
Edit: Koipen just made a beginner's team building guide. Talk about impeccable timing.
_________________ AIM: Fausch 3173 Courtesy of Afonso! ^_^ Time Zone: UTC -4 (EDT) Record: W:66 L:24 Vs. Will: W:18 L:2 I'm always up for a battle!
Sorry guys, I've been busy lately.