Last year's VEX game had one robot that could perform a perfect chokehold. 2W, from Gladstone Secondary here in Vancouver, could expand and form a wall blocking off just over half the goals. Assuming they had a partner who could score 100% of the points that were exclusively available to their alliance following the "block", 2W was mathematically guaranteed a win.
They did the math on this around Christmas time, played out their season and qualified for worlds with a "regular" robot, then showed up in Anaheim with a brand new machine.
It did poorly in qualifying, as they didn't always have a partner able to take advantage of their defensive dominance, but they were selected to an alliance of two outstanding "scorers".
They won the world championship (defeating another Gladstone team in the final) without ever having scored a point in the entire tournament.
Oh, yeah... Gladstone did okay this year, too... finishing on the #3 alliance.
But it was a classic chokehold, planned intentionally, and launched without warning or time for other teams to adapt in any significant way.
http://www.youtube.com/watch?v=gQHD-fleuwY
Jason