Complex sentence: The jump heights in the over fences pony classes are proportionate to the height of the pony, with small ponies jumping 2'3 ", mediums jumping 2' 6", and large ponies with fence heights of 3'.
Split into simpler sentences: The jump heights in the over fences pony classes are proportionate to the height of the pony. For example, small ponies in regular competition jump 2'3 ", medium-sized ponies jump up to 2' 6", and large ponies have fence heights of 3'.