Seriously, you guys sound like you have never played Dream World before. Shandera was the strongest revenge killer in the metagame, nearly every team in OU has him because of his ability to trap the opponent, turn them into a set up fodder or just simply finish them off with a STAB Overheat. Say, you have a ScarfTar on the field, and it just killed the opponent's Chansey with a Superpower. Now you are locked into Superpower and prepare for a switch-out. But the opponet sends in a Shandera. Now what are you going to do? You can't switch out, and you are locked with Superpower, which can't even hit Shandera. Exactly, YOU CAN'T DO ANYTHING. Now you know for sure that that Shandera is gonna fire a Hidden Power Fighting at you, but you can't do nothing other than just click the Superpower button. How does that feel? Frustrating? Well, what if that Shandera doesn't use Hidden Power and use Calm Mind instead? How would you feel now? You start to yell and punch at the computer's screen right? Then how about after getting to +6 SAtk and SDef, Shandera starts to use Minimize? I bet 99.9% of you would immediately hit the "Close Window" button and forfeit that match.
Therefore, I repeat: Shandera is the most dangerous threat in the OU metagame. And after this, anyone who still doesn't believe me, pm me and we shall have a battle at Pokemon Online to see who's right.