With amalgams, having too many on a team meant way too many powers, but with team-based it's easier to form a larger "team" without becoming excessively powerful. 2-on-2 would be fine...but as ScarletSpider's old tourney showed us, with teams it's possible to have more (not that it was a perfectly balanced tourney, but I believe the number was 7). I'd say 7 is way too many, but certainly anywhere from 2 to, say, 5 would be do-able.
I'd vote toward the lower end of that (2 or 3 (4 max)...any more would be a drafting nightmare) but it's certainly possible.
Also, we'd need to start thinking about rough "limits" (like our "Powerful Street" that we invented for this current tourney).