Okay, so here's some kind of explaination to what each character does...
Blue Girl: Boosts you, aim at 45 degrees
Green Girl: Stops you. Or if special is activitated, you would earn the biggest boost out of the whole game.
Purple Girl: Does not do anything when touched, but will stop you from touching a girl character for 1 time.
Yellow Girl: Boosts you, aim at a high angle. The boost is a little bit stronger than blue girl's.
Light Brown Boy: Change your angle (higher or lower), but does not speed or slow you down.
Dark Brown Girl: Boosts you, aim at a low angle. The boost is a little bit stronger than blue girl's.
Blue Boy: Slows you down.