3v3 singles metagame

[Brown]

I go to a lot of anime conventions.
At most conventions they hold Pokemon Tournaments with fairly simple rules.
The one I'm currently going to has the rulings of:
1. No legendaries
2. No Dream World
3. No Ubers (they don't specify what their ubers are)

The battles are 3 on 3 flat singles.
Which pokemon would dominate this type of metagame?