Oooo that's a toughy (: Shantae and the Pirates Curse is a good place to start I believe. That's at least the first game that I started with, and story wise there wasn't anything confusing. After that go with Half-Genie Hero - both are great games!
Would you dig an idea of a fighting game based around music, in which the fighters are based on a music genre and their region of origin (e.g. an English zombie guitarist representing the metal genre, an American curly haired fitness instructor representing the pop genre, an English fat lady with Viking armor representing the opera genre).