Weird analogy that came to my mind in connection to MLP:

Angels have wings and devils have horns.

Hmmmmm...

Nah, I'm sure it's coincidental, but an interesting coincidence nonetheless.

Let's continue this line of thought just for FUN:

heavenly: loyalty, pushing personal limits, trying to be your best, inspiring people | loving kindness, compassion

earthly: hard work, honesty, family | having a joyful time, cheering people up, faith

evil: magic, rational thought, science | worship of fancy stuff, fame and superficiality