Teams sound like a really interesting idea. One potential issue I see with getting people to enter is that, for example, while I'm passable at some parts of making a game, I'm not great at anything. I don't know if there are other newbies like me who feel that they aren't good enough yet to contribute much to a team (and who don’t have any previous examples of their work to show). Maybe random team assignment to prevent all the really good people from joining up as well as to make sure everyone who is interested is able to participate? Or maybe a designated person matches up the teams based on people's strengths? Of course, neither of those suggestions help ProgZmax’s point that you need to have partner(s) who will get things done, as you have no control over who you will be with.
I'd also second the idea of separating background and character artists; I'm OK at backgrounds but I suck at characters!
I'd also second the idea of separating background and character artists; I'm OK at backgrounds but I suck at characters!