I'm morally against the shocker movement. I used to be more of a telefragger/rocket guy, but with all these shockers coming around it has forced me to work on my skills with other weapons. The best way to counter shockers is with the minigun (alt-fire), or if you don't have that, the sniper rifle. Both of these weapons can easily knock these guys out of their rhythm. Also I have found it very effective to always face the shockers. They will shoot the shock ball to where they anticipate you to be, just move away from it and use the minigun/snipe them. Most shockers don't know what to do when you react like this, so they will continue using the shock rifle and end up dead. Many are so set on using the shock rifle, that they've forgotten how to do anything else.