Still think Lucina should have been unique. She cosplayed as Marth but fought like Chrom and Chrom fights nothing like Ike regardless of whatever that Looney Tune Sakurai thinks.
The problem is, in Fire Emblem games the characters have very few moves as is. The character's moves are mostly made up on the spot based on a concept. Ike in Smash doesn't fight that much like Ike in Path of Radiance/Radiant Dawn, either. He uses Aether, he performs his killing critical attack (Quick Draw), and his Eruption (which was originally supposed to be his Ragnel shockwave) is based on the Bolganone animation.
Some of the animations are slightly different from game-to-game, and character's fighting styles are inconsistent, as well, because they're based on the class. When you can get actual Marth as a Spotpass or DLC character, he uses Lucina's model. Now from an appearance point of view, Lucina and Marth fight exactly the same.
The translation to Smash means absolutely nothing. Characters are based on a vague concept. Marth was based on a sword fighter, then later specifically with mostly thrusting attacks, which is the case with many Lords. Lucina, as she disguised herself as Marth, fit being a Marth alt perfectly.
Such was not the case with Chrom. Chrom could have been an alt for Ike. And Ike even does have Chrom's colors as a skin. That said, he didn't fight exactly like Ike in Awakening, and he certainly didn't disguise himself as Ike or anything. Ike is portrayed as a Hero when he's a spotpass character, as is his descendant Priam.
Of course Chrom -COULD- have been a separate original character. The issue is, he wasn't really all that interesting as a separate character. Frankly, I'd say the same thing about Shulk. They had to give Shulk a stat-changing gimmick to make him interesting.
There's a limited amount of things you can do to differentiate characters from the same franchise who wield the same weapon.
The only FE character I can see myself getting behind at any point is Kamui, however, I am currently opposed to their inclusion right now until AFTER their games are released. Which is not until some time next year for the western world.
I can't really see Kamui getting into Smash unless Kamui has the ability to use any weapon (Kamui's base weapon is a sword, but maybe Kamui can be customized to use different weapons). The problem is, the Dragon concept I can't see working in Smash Bros.
If we were to get an If character, I blatantly think it'd be Aqua. She'd be far easier to create and would represent another central weapon of the FE series, as well as have an original fighting style through dancing. Not even Kamui's fighting style really is all that interesting without the Dragon.