Yesterday we learned that Lucina will be a clone of Marth in the new Smash Bros., which is fine by me, but Chrom will not be making the final cut. Director Sakurai explains that he was initially considering adding Chrom, but called him "another plain-old sword-wielder like Marth and Ike" (ouch!).
Robin was then added instead because he possessed unique characteristics. Lucina almost got the costume treatment, but eventually he decided to give her a roster spot. According to Sakurai, she was "lucky," and will be an easier fighter to pick up for beginners than Marth.
I'm going to play the sh*t out of all of these Fire Emblem characters.