Here is the Pokemon DB Glossary page for various terms, but Pokemaster has not updated it yet.
For our current full list (more will be added), click here.
And OU stands for Overused, which refers to the Pokemon commonly used in the Metagame of the competetive Pokemon play.
If you have any specific terms you need explanation for and it is not on the list, you can comment this answer or something.
- 03.10.2012 11:09p