Ami - or Amy, in the English dub - is Sailor Mercury. The smartest of the Senshi. She is good at maths, computers, and science, as well as apt in language, and that's probably the tip of the iceberg. I'm fairly certain that she was the second Senshi, but I can't be sure because when I think back all I see is Sailor Moon getting her butt kicked and Luna telling Ami to say "Mercury Star Power!" and I have no idea where Mars was at this time. Sailor Mercury's powers are to do with ice, rather a contradiction seeing as the planet Mercury is closest to the Sun, and the god Mercury was actually a messenger god and has sweet bugger all else to do with ice [to my knowledge]. But, I guess that it has to do with your elements and extremes.