So it's very Darwinistic. The toys that don't work die. We asked some girls to tell us a story of what the superheroes' exploits would be once they found the ultimate evil Dr. Nogoodnik. They wanted to rehabilitate him. Boys would tell you in gory detail how they'd draw and quarter and do all sorts of horrendous things to finish him off.
Transformation is big.
You also see it in toys that are designed to transform from one kind of vehicle into another. For boys, however, the transformation is generally from less powerful into more powerful. Girls want to become more glamorous and magical. Kids also have a lot of fears that come from being small in a world of large and powerful things. They fear the breakup of the family, and they fear toxicity.