Let me quote Dandy from the discussion thread about the rules for "One for All":
4 players are better for a tournament (in general, an even number of players in a team) - as it creates more balanced team compositions.
5 players are more convenient for organization (an odd number of participants in a team) - as it reduces the chance of a draw in a particular series.
Based on the number of registered players, I'm in favor of 4 people per team.
The more people in a team, the smaller the variance between skill levels within a single group, and the more balanced the compositions in each group - this is simply logical.
