If the design of your event permits participants to form teams prior to the start of the event, the "Find a Team" page can be found on the challenge platform and can assist with this process.
This element allows registered participants to see the teams that have already been formed. Within the team cards of the formed teams (as pictured below), a participant can view team details, message a team, or request to join a team. Messages and requests to join will be sent to all existing team members and will be received within the challenge platform.
For this page to be visible for participants on the sidebar, you will need to enable "Visible Teams Page" under "Feature Visibility" in the "Team Settings" section.