If I were going to make something like that I'd probably have an array for different types of movement. IE MovementTypeOne[] = ["left", "left", "left", "left", "down", "right", "right", "right", "right", "up"];
then have a switch statement for each direction and move all the units in that direction. at the start of each loop move the max hight down by one.

I'm also very naïve, so I'm probably suggesting something horribly wrong.