If you click on the link on the front page that talks about the rules it takes you to the following link. I cut and pasted the section that discussed monsters. It was the only link I saw reguarding the War, so if there is another place to get the current rules, please post the link when you have time.
Again, if I can do anything to help, let me know.
http://worldbannerwars.org/forums/showthread.php?t=18
Team Composition Rules:
1. Teams are comprised of 14 people and up to four alternates.
One person from ea team may choose a monster from the predestinated list provided.
2. Alternates may be swapped into the active line-up between rounds.
3. Team members (including alternates) are assigned classes before the tournament starts and may not switch classes.
4. Your team may have one of each magic using class.
5. Teams may have no more than two bows.
6. Teams may have only one siege weapon mounted on the aft castle of ea ship.
7. Players may only sign up with one team, though pages may be shared
8. Teams do not have to all be from the same company, household, kingdom, etc. They merely need to all play together and present a banner with a unique symbol
9. Banners must be a MINIMUM of 2' x 3' (2 feet by 3 feet) in size and reflect your company/household/team's symbol on it.