You have to be able to effectively present your horse to the judge.
Thus, the horse needs to learn to walk and jog beside you, on a loose lead shank, and be trained to set up quickly, and stand squared up while that judge walks around him. If you can't set him up quickly, he might have good conformation, but that will be missed if the horse is standing funny, moving around ect.
While not a showmanship class, you still need to know where to stand, in relationship tot he judge.
Mares and stallions have to be used to having their teeth shown