Spike: He seems to really want to feel important, he gets pretty down when he doesn't feel needed, sometimes he takes on bigger challenges than he can handle to show he is useful though. He just loves helping ponies and is very selfless, which is amazing because it goes against his dragon nature. He loves to feel appreciated and he loves to see he's the reason why he made someone happy.
Twilight sparkle: She is book smart but didn't start out exactly 'street smart'. She's a huge 'teacher's pet' and scared of disappointing Princess Celestia. She stresses over small things, gets obsessed and freaks out over things too. She's very organized and a perfectionist for she does this in her spare time, she's also very modest and doesn't want to seem better than anybody else. She just wants to help everyone else learn all she can teach.
Fluttershy: When you think of fluttershy you think social anxiety, she hates being the center of attention, she's very nervous and sort of on edge all the time. She is obviously extremely kind, and doesn't want to hurt or offend anyone, although this can backfire for she can be taken advantage of very easily. She does come out of her shell and has no problem speaking up when the topic of animals comes up though, or if someone is being rude to an animal or her friends.
Rainbow Dash: She loves her reputation of being cool and doesn't want to ruin that rep, she likes being the center of attention for her awesomeness, she's not modest at all about it and wants everyone to bathe in her glory, which could annoy some ponies....She's clearly a tomboy, she loves to win and prove that she's the best, any opportunity for that she can't help but to take it, she's very competitive. She loves to prank and joke around and have fun, while most importantly looking awesome doing it, as long as it doesn't hurt her friends in the process of course.
Pinkie Pie: She's full of energy, has strange and unusual things about her nobody else can understand. She's very random and seems to not even make full sense sometimes. She LOVES to make ponies smile, laugh and have fun, that is most important to her. Sometimes her energy is too much for ponies to handle for she never shuts up! She's very optimistic and is never disappointed and is impressed and excited by many things. She's very friendly and outgoing.
Rarity: She is a very hard worker and very patient with other ponies, she goes out of her way to help other ponies even if it means more work for her, and is dead set on doing the absolute best she can and will not settle for less, a perfectionist. She is a drama queen and exaggerates things but is able to handle things herself and get what she wants, usually by using her charm and/or manipulation. She likes everything to be very neat and clean looking, the appearance of things is very important to her. She likes being seen as a classy lady and really wants to get popular as one.
Applejack: She is very responsible and is very hard working, she likes doing things and handling things herself. She is very family-oriented. She doesn't care about getting a little dirt on her hooves, as long as it gets the job done. She's very down to earth and not a complainer, she does what she's got to do, but she doesn't like disappointing anybody. Sometimes she can keep things to herself a little too much and not ask for help, she can bite off more than she can chew sometimes, and sort of lacks manners.