So my question is, yes it is based on a team but can there be 3 main characters?
Yah I have the same question 
Yes, you can have multiple main characters, as this challenge is based on you or your team’s experience. The amount of characters is not restricted, just be sure to meet all the Requirements listed in the challenge, and also review the Judging Information section: “The subject matter should reflect the items listed above, namely a challenge the team faced, what was learned in the process of designing, building, and programming a robot or how the robotics experience inspired girls to pursue STEM and/or education fields/careers.”
Good luck!