Alright,here are the roles of Moondancer and Starlight Glimmer in PLM:

Moondancer is Sunsong,a friendly,outgoing mare who was once a good friend of Eclipse before she turned evil. Although,she was kind of a jerk back then. In fact,Sunsong turned nice right around the time Eclipse turned evil. When Eclipse returns to Canterlot 5 years later,everyone was cold to her(especially Minuette/Tango)except for Sunsong.

Starlight Glimmer is Cloudshade Clear,a heroic mare with bad intentions(If that's even a thing). She wants to confiscate everypony's cutie marks and put them on herself,but tells everypony that it's for the sake of equality. The reason she does this? When she was a filly,she had a friend named Moonform(Guess who THAT is?),but their friendship was torn apart after Cloudshade earned her cutie mark before Moonform earned his,and she endlessly bragged about it. So now,Cloudshade goes out stealing everypony's cutie marks so that she can prove to Moonform how special cutie marks are. Clearly,Cloudshade is a WAY bigger jerk than Starlight. So,once again,I need help;Will Cloudshade redeem herself and join the Tail 6,or will she stay evil and join the Mane 6?