This sounds like a grand idea, I wish you the best of luck with it! The Britannia Guards can provide a team, and I'm hoping other "competing" guilds, such as Cove and Vesper will as well. Then we'll obviously have the pleasure of beating them.
A quick search on Google gave me this result as to the rules of bagball:
OSI Bagball Rules
If someone has the time and energy, we'd be very grateful for the contribution of an article on
bagball on the
MoongatesWiki.
Bagball - MoongatesWiki is a good start.