Pretty much agree with Zero. There's a misconception that J means judgmental. It has to do with which function you extravert. I agree RD is kind of a [bleep] but if you'll read up on cognitive functions, you'll realize she is a P through and through (extraverts Sensing).
As for the 16 types, there's a few MLP charts floating out there but my favorite is this one: https://knowyourmeme.com/photos/887277-myers-briggs-type-indicator-mbti
Although I don't agree with all of the assessments (Luna is way off), it's still reasonably good. I've agonized over Fluttershy more than the others. One one hand, she has some of the external characteristics mentioned in Keirsey's ISFP description (kindness and love of animals). On the other hand, the overall personality doesn't really fit her. ISFP's are generally more laid-back and carefree. (DJ Pon-3 might be one, for example) I've pegged FS as an unusually kind, animal-loving ISFJ.
To me Twilight Sparkle seems more ISTJ in FIM, INTJ in EQG.