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I think the best option would be to say that a host could simply choose 6 of the 7 categories and let them pick whichever they felt like would generate the most interest in their playgroup.
States and Regionals almost always run 2 days, so requiring teams to be a part of the mix is not a huge stretch.
Why would it be hard? Just give both the players points for winning separately.
Also, I think we should make it a rule that you can play enhancements on your teamate's characters. That would be awesome!
I don't think Mark had the outside knowledge to be aware...