Thanks for the question about the number of team members.
Previous competitions have taught us that often team members have to cancel or get sick prior to an event. Instead of being short a member or having to recruit someone who hasn't trained with the team, having 6 provides a couple of alternate members for the competition.
Additionally, teams can choose which members compete in each stage as some may have stronger skill sets or experience that match the competition stages. All team members will still have access to the event and an opportunity to play at the open games on the day of the event.