[Jeff Rodriguez]

Three decent shooters, all with strong drive trains.
It's simple. Two robots cannot shutdown three robots. With three decent shooters, you can't defend them all. While they're on offense, they all shoot. The two defensive robots can only guard against 2 others, leaving the third open to score. When the balls start filling up the goal, the defensive robots slide, leaving a different robot open to score.
It's just like playing man-down in lacrosse, except everyone has the ball.
One team starts scoring, slide, another teams scores...repeat for 40 seconds or until the match is finished.

The strong drive trains comes into play during their defensive period. Each robot has to be versatile so that they can play solid defense.
I've seen this tactic win at least three regionals so far.