Do you have any advice on how to stop a pony from kicking at other ponies while being ridden by a small child?
Bad habits developed by horses can be hard to break, especially in older horses, because often horses that kick have been allowed to get away with it. Horses that kick usually are dominant or fearful. A novice or recreational rider would not be able to change this behavior. The rider has to establish that he/she is dominant and then protect a fearful horse or discipline an aggressive horse. I would advise talking with professional trainers in your area about this behavior and how they might go about changing it. On the trail, however, tie a red ribbon high up on the horses tail to alert other riders not to ride up behind this pony because it will kick. You could also have this pony ride at the end of the pack when on the trail.