Mega-Girl (Martine "Marty" Penn), ‘Megs’ to her friends, is actually Marty Penn, a shrimpy little guy who can create a psycho-kinetic ‘shell’ around himself that takes the form of a tall, shapely, busty blonde.  Marty is in the Class of 2009 (a sophomore in late 2006) and rooms with Delta Spike. Her parents, NYPD Sergeant Michael Penn and a stay-at-home mom, seem to have accepted his transgendered status, even if his father doesn't really approve.
As Marty, Megs is just a shrimpy little guy. With her "Mega-Girl" shell up, thought, she becomes a young blonde bombshell, with an hourglass figure and C-cup breasts. At 5'5" and 120 lbs, she's no amazon, but she looks more mature than she actually is. Her face is reminiscent of Hillary Duff, with cornflower blue eyes and butter-yellow long, blonde hair, which she wears loose. Marty is transgendered, and is taking advantage of the long-effects of the PK shell to turn her real body into the likeness of Mega-Girl. It's a slow process, though, and she is a long time away from being able to have actual sex with a guy.
Normally a very withdrawn, depressed type, as ‘Mega-Girl’, Marty becomes positive, out-going, friendly, and a tad over-enthusiastic. Following on the example of her police officer father, Megs is eager to put her powers in use to the common good. She has been importuning the Empire City Guard on holidays and vacations, and hopes they will accept her application when she turns eighteen. Megs is very much a part of the Cape Squad, and is bumbling around trying to get something started with Iron Star (yes, this doof really named himself ‘Iron Star’), one of the leading lights in the Cape Squad. Megs is considered a bit of a ditz. She's frequently strapped for cash, since her father is not really willing to spend a lot on new girl clothes.
Mega-Girl is a "telekinetic supergirl". She is a MAN-4:a. She is able to form a PK "shell" around her body, and while the shell is active she is super-strong, very tough, and can fly. But, remember, she’s still learning the intricacies of her powers; she can’t really control her strength, and has a tendency to go blundering through things. A secondary effect of her PK shell is that it slowly reshapes her body in the likeness of the shell. To further that goal, she keeps the shell "up" as much as possible -- with practice, she now can keep it up pretty much indefinitely, even when sleeping or otherwise unconscious. In another year the exterior change should be done, and around 2010-2011 she'll be completely transformed, inside as well as out.
She's a sophomore; we don't know what level of classes these are.