This is an old topic from a few hours ago but I wanted to clear a few things up. There seems to be a lot of misinformation and miscommunication.
It
does make sense for Chrom to be an Echo of Ike.
Canonically, Chrom taught himself how to fight and he taught Lucina that style. While Lucina is an ancestor of Marth, uses his identity briefly, and shares a lot of visual aspects with Marth,
Lucina is the one out of character. It wouldn't be wrong for Chrom to fight like Ike because he's supposed to be like Lucina,
Lucina is the one who is supposed to
be like Chrom. Chrom -> Lucina, Chrom is the originator.
Take for example in Warriors, Chrom and Marth were their own characters with original movesets. When Intelligent Systems pushed to add Lucina late in development, who did they make her a clone of? Was it Marth, the character who she's already been a clone of? No, it was Chrom, because Lucina is supposed to be like Chrom. Chrom not being like Lucina doesn't hurt him because he is the one staying most true to canon in the scenario that he takes Ike's brash and aggressive style that Chrom himself is known for. And bashing Chrom by saying Chrom and Lucina's swords are supposed to be the same, that it would be weird if Chrom wielded it two-handedly? That's the canon, the Exalted Falchion and the Parallel Falchion are big two-handed swords. Lucina's Parallel Falchion was sized down to fit Marth's Falchion. "Aether is Ike's signature move, no one else can use it!"... When Aether is a signature skill of Chrom
and Lucina? Even in this
cutscene, while not exact, Chrom is basically doing "the Ike jump spinny move". (You also see that they are using their Falchions two-handedly)
A lot of confusion and controversy comes with how Awakening was designed, it was basically a last-ditch effort to include basically every design and mechanic in the series in one large final amalgamation of a game. Even Sakurai called it the "definitive Fire Emblem". Lucina sharing Marth's visual design, Chrom having a brash non-royalty style like Ike, Genealogy's 2nd generation, Rescue being turned into pair-up, being technically set in Archanea, and other references
littered everywhere. Pretty much everything in Awakening is a mix and match of old archetypes to call back old games with new tropes to appeal to a new audience. Lots of Awakening is inherently not unique, lots of it is designed to be like old things, so that's why Chrom makes sense as an Echo of Ike.
Do I want Chrom in Smash? Not really, he and Awakening have had their time, and I don't care for him too much. Should he be in? Yeah, Chrom should be in. While it would be a bit disappointing that 3/7 of the characters would be from one game, it's pretty much already there. Chrom has an HD model for Robin's victory animations and Final Smash. The fan demand exists, FE is mostly Awakening and Fates now and Awakening was still relevant near the ballot (Fates didn't even exist.) Chrom must've placed highly to get a Mii Costume for consolation. Chrom as Ike works, just make Eruption have white flames to represent the titular Awakening or electricity (don't know about that yet from Awakening but I know he uses it a ton in Warriors.). We've already gone over Aether, Chrom has the skill and can perform a move close enough to it. If Echoes have minimal changes like no tipper and Electroshock/arrow trajectory, this could be where Chrom could be a bit different by having his Aether a straight jump without the sword throw and a bit more horizontal movement than vertical. Other than those minimal changes, slap Chrom onto an Ike skeleton model and you're good to go. We have reason to believe that there is space for Chrom, Ike's Chrom inspired color palette has been removed and Robin's origianl Final Smash and victory animations which featured Chrom are no where to be found. Chrom is definitely possible as an Ike Echo, and he should be at least suspected as one.
I'll start a petition to add in the Blazing Sword trio once it gets a remake though.