I’m trying to compare the members of the Shadow Six to the Humane 6. I’m not really sure about the roller-skaters (Lemon Zest and Sunny Flare), but I think the rest match up with what we’ve seen so far. I’m basing this off the Hasbro Equestria Girls website (http://equestriagirls.hasbro.com/en-us/girls/fg/twilightsparkle) along with the trailers and my own guesses and perceptions.  
Human Twilight/Fluttershy: (It’s implied that Sci-Twi has at least some of Princess Twilight’s characteristics such as her curiosity, but I’m comparing her to one of the Humane Six as well.) Common characteristics: polite, submissive, not athletic, archers  
Sour Sweet/Applejack: Leaders/second in command, athletic, honest, has a bit of a temper, archers  
Sugarcoat/Sunset Shimmer (before redemption): Intentionally hurtful, a bully, motorcyclists. (If you watch the first trailer carefully, you can see that Sunset clearly doesn’t like Sugarcoat’s jabs at Twilight; maybe this reminds her of her former self?)  
Indigo Zap/Rainbow Dash: competitive, very athletic, wild, motorcyclists  
Lemon Zest/Pinkie Pie: comic relief, in their own world, ditsy, roller-skaters  
Sunny Flare/Rarity: detail-oriented, perfectionist, roller-skaters