They can give Chrom any skill he could reclass into, as well as moves original to Smash. Correct me if I'm wrong, but I don't believe that Ike had the Eruption move in his games.
Seriously, anybody who thinks Sakurai can't make a unique and fun moveset for any character needs to take a long, hard look at the roster of every game in the series.
Wait, you're arguing that Chrom isn't interesting enough and you want the Marth lookalike instead?
I'd enjoy Lucina just as much as Chrom, but visually she is so similar to Marth that I can't see her getting in as a separate character. Unless they give her a significant reworking she creates too much potential for visual confusion.
You're not giving Sakurai anywhere near enough credit.