Allow me to share my controversial views on this, even if you are attracted (I personally am not attracted to them.) to adult MLP Ponies, it wouldn't be bestiality (it be Xenophily, which is OK), since they aren't the same as animal Ponies of our world. For I believe as long as both species are sapient minded (Like MLP Ponies who have a society, culture, laws and infrastructure and whatever just like us Humans), doesn't matter how different they look and if they can give consent and consciously