Applejack

 

good:Has a strong sense of right and wrong, nearly always keeps her word. A very hard and diligent worker. Family and friends are very important to her. Is mostly level headed, mature and wise.

 

bad:Can be very stubborn and set in her ways and often has a habit of overdoing it.

 

 

Twilight Sparkle

 

good:Has an inquisitive mind with a strong thirst for knowledge and love of learning. Is slightly ambitious but not the point of arrogance and has the patience as well as willingness to put in the hard work to succeed.

 

bad:can sometimes lack basic common sense aka "street smarts" and in some cases has been shown to fairly closed minded. She can sometimes be slightly anal retentive and also struggles with social anxiety and severe OCD which thought has gotten better is still quite a struggle.

 

Rainbow Dash

 

good: Is very loyal and will not hesitate to stand by her friends when they are in need. She has ambitious goals but is willing to put in the hard work and sacrifice to make them come true but without compromising her principles.

 

bad:Can sometimes be extremely arrogant and struggles with some very deep seated insecurities about showing emotion and maintaining her "rep".

 

 

Pinkie Pie

 

good: Is very friendly and has a positive attitude and a sincere desire to make everypone smile.

 

bad: Has almost no concept of personal space and can sometimes go into creepy stalker mode. And sometimes struggles with when to be silly and when to be serious.

 

Fluttershy

 

good: Is very kind, gentle and compassionate.

 

bad: She seems to learn a lesson and then forgets it a few episodes later making her as a character a bit inconsistent.

 

 

Rarity

 

good: Can on some key occasions be generous, and is often willing to go to great lengths to do things she wouldn't normally do to make her sister Sweetie Belle happy.

 

bad: Can sometimes be selfish, shallow, vain over dramatic premadonna.

Source: Good and Bad qualities of the Mane 6