Heavenspent was born an alicorn, a rare thing indeed. Also unusual is the fact that he's an adult pony who never earned a cutie mark, which he attributes to his "being equally perfect at everything!"
Starstrike doesn't agree that friendship is magic. Only magic is magic, which is why he replaced his horn with a far more powerful crystal, with which he probably aims to take over the world, because he lost his professorial position at Pony University so what else is he going to do with his time?
Cold Money and her son Precious Little are aristocratic ponies. The fact that random non-noble ponies can be granted princess titles and alicorn status has triggered many letters of complaint to the powers that be. That's no way to run a government. What's next, democratic elections of pony prime ministers??? Perish the thought! They'd be antagonists for an episode about how money can't buy happiness and talent can come from anywhere, even commoners, and be defeated by the power of friendship.
Now everything I know about the show comes through cultural osmosis. I don't know if the ponies go to pony college or if they have hereditary nobility… but now they do.