Amy is without doubt the brain.  School work is usually her top priority.  Amy is about the only scout the is not boy crazy.  Don't get me wrong here, it is not that she isn't  interested in guys, she just realizes that there are more important things.  Amy's 'love interest', Greg, appeared for only two episodes.  Those are about the only episodes where Amy is interested in a guy.  Occasionally she admits a guy is cute, but she does not obsess over it.  She is just pretty level-headed when it comes to guys.
    She may seem like just a brain, but Amy is also a really good friend.  She allows sometimes herself to get away from the books and do something else with her friends for a change.  So Amy is not a total bore.  And besides, the Sailor Scouts need a brain so they can figure out all the technical stuff, right?  Amy also loves and is a really great swimmer.  So all her talents do not always involve her 'smarts'.