Smash idiots fail to understand that FE is a game that is known for having a shitload of characters. The only mainline Nintendo series that has more in terms of playable characters in the fucking series is Pokemon.
You know the series with nearly a thousand creatures, not to mention around 100-200 human characters of varying importance.
FE has at bare minimum, if you also include prominent enemies and NPCS, around 30-60 characters per game, minimum. The post-awakening ones easily go north of 50 per game. .
at this point, Marth/Roy/Ike are kinda just thrown in because while Marth is the first FE MC, Roy/Ike were introduced before the FE character boom. Then we had Robin and Lucina. I'd argue that Lucina may have been unnecessary to an extent but all they needed to do was give the Marth model longer hair and titties. Chrom was just there because I guess they had the model from smash 4. Corrin/Byleth popped up as DLC reps for their respective games being hot and fresh at the time of DLC release. Robin/Corrin/Byleth have variety in their moveset. This differentiates them to an extent. Roy/Ike are sorta legacy cases, but it's fair enough to let them into smash ultimate since the tagline is "everyone is here".
I guess the real crime is Lucina being slapped in as an easy echo fighter clone of Marth. Buuuuut, she's not the first one of that type. The fact that her sole difference in playstyle from marth is that she doesn't have the funky hitbox dipper thing that Marth's known for.
Chrom was an easy add. They had the model, and he's just Roy with Ike's up-B in terms of special moves.
Out of all the major FE characters they could potentially add, there's issues with most of them. Eliwood's just Roy in terms of how he'd play. Lyn would just be a swordlocked Sheik.
Hector/Ephraim have other weapons sure, but their days of popularity are a little behind. If one of them debuted in brawl, that'd be another story. Sigurd/Seliph/Leif are sword-locked characters that only hardcore FE fans recognize due to being JP-locked. Eirika would just be another sword-lord and has even less of a fan following than Lyn.
Who does this leave? Certainly not Alm and Celica. Despite the remake, Echoes of Valentia, selling decently and being a well made game, they're essentially not really viable for variety's sake. Alm would just be a Marth/Ike hybrid with maaayyybbbeeee Double Lion getting repped as a special move. Celica would just be a speedier Robin.
So, what about the secondary sets of Lords from FE Fates and 3 Houses?
Fates isn't the brand new baby any more. The lords in those games would just not really be applicable for a full creative moveset except for maybe Camilla who uses both an Axe and Magic. Sakura also dual wields a bow and staff. However, Sakura ain't popular enough, and the non-Camilla options are either rangelocked and would just be sorta boring, or sword mains and would just invite more salt. Hinoka/Elissa/Leo/Sakura/Takumi aren't popular enough and don't have creative moveset options. Xander/Ryoma are fucking sword users and it'd just be derivative since they're orthodox sword users of their respective styles. So that leaves. . .Camilla and possibly Azura. (I don't care about spoiling Azura, FE Fates Revelations is a horrible game.) Camilla uses an axe and magic. That's potential, but the window's expired. Azura's a support unit who uses lances for combat. She's got jack shit for a moveset.
So this leaves the 3 Houses lords. Claude's a bowman who hasn't shown much in the way of canonical CQC. He's out.
Dmitri and Edelgard have canonical fighting styles and "character" that could be in their movesets. However, it makes more sense from a marketing standpoint to just have Byleth use their weapons and be the face of the game given they're the literal MC.
What's absolutely fucking hilarious about all this is that you can only argue that maybe Chrom/Lucina are just derivative and slightly unoriginal out of the existing FE roster in Smash. However, they're just easy echoes to slap on and buff the roster number. The 3 "avatars" in Robin/Corrin/Byleth have M/F versions you can switch between and aren't solely swordlocked. Marth's the OG MC so he's an obvious lock-in. Roy/Ike are kinda legacy cases that rely on their source games for some inspiration. Roy's fire based moves make sense in context of his base game. Ike's got 2 model sets from both of his games present, as well as a moveset appropriate to him. Additionally, his final smash is something that is potentially canonical from his base game as it just appears to be a buffed up aether.
Anyways, Smash fans being salty over Fire Emblem will never not be hilarious. In another timeline, F-Zero went on to survive and FE got shitcanned after the gamecube. In that timeline, Smash fans sperg out over the addition of 9 F-Zero characters that all have the same final smash.
