Hi Caitlyn,
A team needs to participate in all of the events (Deign event, men's speed event, women's speed event, and endurance event).
Each event has it's own scoring, which in turn is required to calculate the overall team scoring.
If however, there is a case where a team does not have riders of both genders, they can skip the particular event, and they will not be scored for that particular event.
Ankur Singh