Because of my horrible brain disease that forces me to think of all things in terms of kung fu movies eventually, here is what the mane six’s fighting styles are.
Applejack uses Krav Maga, which like her is simple, brutal and direct. No fancy moves or shouting her attacks, just “fuck you, I’ve broken your arm.”
Fluttershy, being Fluttershy, prefers never to directly attack and thus practices Judo, where she tries to get her foes to defeat themselves by simply redirecting their force when attacked.
Rainbow Dash of course wants to attack with as much speed and showiness as possible and fights using what she calls Taekwondo, but mostly its just flying at something really fast a punching it over and over again while shouting “Hi-yahhh!” a whole lot.
Rarity is a master of Silat and is infamous in the underground fighting circuit under the name “Gemcutter” for being almost unbeatable, and for having accidentally killed her last opponent in the ring, something which haunts Rarity to this day.
Pinkie Pie is a drunken master, give her a belt of whiskey and she will demolish all challengers in a wide variety of comical fashions.
Finally, Twilight Sparkle is attempting to develope a whole new martial art out of the best of her friends techniques, with mixed results largely because the only pony who is both competent and willing/able to train Twilight is Applejack.
In terms of skill and lethality, I rank them thusly:
1.) Rarity
2.) Pinkie Pie
Rank one and two are difficult to determine because both Pinkie and Rarity are absolute and undisputed masters of their respective martial arts and have never fought each other because Rarity is terrified of her own skill and has vowed never to use it again.
3.) Applejack
4.) Fluttershy
5.) Twilight Sparkle
6.) Rainbow Dash
