Okay, so I've got a trap. A circlish one on the ground, one that opens with a button. When the button is pressed, the trap will open, with the top right quarter moving diagonal up right, bottom right quarter moving diagonal down right, bottom left quarter moving diagonal down left, and the top left quarter moving diagonal up left. You get the idea. Problem is, I'm not sure what to use.. Is it func_door or func_plat? Func_plat doesn't seem to work, to the best of my knowledge, it only moves up and down. Func_door moves left, right, forward, and backwards only..

A func_door can move
Up / Down / Left / Right / Forward / Back

and diagonally, if you set the angle to do it. So, probably
func_door is the right one :)