Of course you can play. There's a simple procedure you can follow and then you can get started. First, you'll need to post the information found here
. (You can post it in this topic if you want.) Make sure you have all of the required parts filled out. You can look further down that link for more detailed information on each field.
Once that's done, you can wait for a staff member (such as myself) to approve you. In most cases you will be, but if we do find something wrong we'll do what we can to help you out. Once approved, you can create a topic on the Member Profiles board. You'll get more on that when you're approved.
Afterwards, you'll create your Secret Base in the Secret Bases forum. This will tell Refs how much you can train, how much you can plant, or how many Pokemon you can catch per day (through "Charts"). Your secret base is also where you will train and plant, and the rules for doing so are found in the Secret Bases forum.
After that, you're free to do whatever you want. You can look for Pokémon in the Wild Pokémon Area by creating a topic there, you can start a CYOP if you wish, or you can challenge other members (or gym leaders) in the Challenges forum. Most battles take place over a messenging service (such as AIM, MSN, or the two chatrooms), though they could be done on the forum if you so choose.
If you have any other questions, feel free to ask them. Thanks for coming to BPRPG!