They were designed to act like house robots in robot wars. I am not sure if they generate a score. They were designed more to be challenges than challengers.
The API docs point out they can't generate score. They can't damage bots outside of their border area, either. However I have a feeling their bullets can still intercept other bullets whether or not they would have dealt damage, and in the 1-on-1 rumble bullet shielding is still pretty effective even without directly dealing damage. So hypothetically, a team comprised of mostly (but not entirely) bullet shielding border sentries has some potential.