Sailor Moon, or Usagi Tsukino, is the head of the Sailor Senshi, although most of the time she is not fit for it. When it comes down to it, she is a coward, a cry-baby, and a dunce, but when she is needed she is always there. Her loyalty and self-sacrifice have helped others greatly in battles, and she is the future queen of Crystal Tokyo.
You will have Sailor Moon throughout most of the game, so you have to use her whether you like it or not. However, this isn't as bad as it sounds, as she has some pretty useful techniques. While not always the attacker, she does come very useful when healing with link techniques. This can easily be made up for when she uses the MoonCup1 to become Super Sailor Moon.
Her weak attack and HP rating cause Sailor Moon to be flawed in comparison to other characters. Be sure to have her accessories compensate for what she is lacking.