Some of you are insane. Fire Emblem has been a pillar for Nintendo since the 80's, nearly as long as Mario or Kirby, y'all act like it's some niche series or something and then turn around and think Rex and Pyra should be in instead even though that's a vastly more niche franchise. I will agree that the saturation of FE characters is a little much, but at least it looks like Byleth is going to be playing differently than the other sword characters. Give it a chance before you scream at Sakurai.
Can't believe I'm saying this, but people could really take a bit of courtesy from the Pokémon crowd's ethic that every Pokémon is somebody's favourite.
SSBU is tremendous but the majority of the newcomers have totally whiffed for me in terms of stirring up the excitement that others felt over Banjo. If we're talking about the characters just as characters (and not how well they play as fighters in the game, because most of these designs have been terrific), the newcomer roster has given me very little. The most exciting announcement for me was arguably Piranha Plant.
Byleth was far down my list and I would have preferred any of the lords, or other first-party picks from the 2010s to rescue the likes of Wonder-Red from obscurity—but I was desperate to see more FE in the mix, and you're damn right I'll take Byleth.
FE has always deserved the royal treatment of a top-tier Nintendo series, and I will always have the utmost respect for Sakurai for almost single-handedly making it so.