Are there other collective nouns for ponies?
The collective noun for ponies is a string of ponies.
A string of ponies is traditional for a group of ponies owned or
bred, usually for a particular purpose. That collective doesn't
apply to all situations where there may be a group of ponies.
Random groups of ponies could be found in many situations, a corral
of ponies, a parade of ponies, a family of ponies; or even more
fanciful, a pile of ponies, a party of ponies, or a plethora of
ponies.