Starting as young horses, you can start to assess if they're going to excell in anything. Babies BUILT to sliding stop will slide in the pasture.

Western pleasure kids will move pretty.. through the hock, flat up front from a few months on. I don't like to assess them from the get-go, because they have to figure their bodies out.

The pleasure horses, which I know the most about, will be for the most part friendly and laid back, as well as exhibiting the movement. They'll travel with their necks level a lot, and won't really want to go anywhere fast. Once they're under saddle, they should be easy to break and pretty mobile, like you can start to catch their shoulders or hips at an early age, I like them smart!