Alright, for no particular reason, I am going to present:
Delay Theory™
The Theory That Doesn't Really Tell Us Much If It's Correct, And Is Almost Entirely Speculation!
As a few people have already said or thought, there are several reasons to believe that Byleth was not meant to be fighter 5 of the first fighter pass. Here's some of the most important facts to back up this claim:
- Byleth's moveset, while more unique than most Fire Emblem reps, doesn't seem as fleshed-out as it could be. The concept of a "weapons master" could go WAY farther than just this, and Sakurai is better than this at making incredibly unique movesets. (Not that it's terrible, while I'm not a fan of it it's certainly pretty cool, especially Up-B and Neutral-B) Compared to the rest of the fighter pass, Byleth's moveset feels a lot less unique and different. Joker practically has 2 movesets (with and without Arsene), Hero has like 40 special moves and critical hits and an MP system, Banjo has three special moves that are unlike anything we've seen before, and Terry managed to be even more impressive than Ryu/Ken already were. Byleth, in comparison, feels lackluster. At least to me, it screams that it was supposed to be more, but they didn't have time.
- The first fighter pass was bundled with a Rex mii costume, and was specifically mentioned to be chosen because he was "too late" to get into the base roster of Smash. Why then, in that very same bundle, is a character from a game released AFTER Xenoblade 2 made fully playable? Considering the timeline of deciding the fighter pass characters and the Rex costume, it feels wrong. Had Byleth come out in the second fighter pass, even as the first one in that pass, nobody would have bat an eye at the Rex confusion.
- The characters in the background of the Fire Emblem stage are considerably less polished than you would expect them to be- and the reason why, is that they're apparently directly ripped from FE3H. This is a pretty huge contrast to Joker/Hero/Banjo/Terry, who all have cameo characters in their stages, and all of those cameo characters' models were made specifically for smash, likely from scratch. (or at least polished from other games)
- Several insiders, including the Two Who Shall Not Be Named, seemed to think we'd get a Smash reveal at TGA until the very last minute, and even then thought we'd get a reveal in December. Sure, insiders are wrong all the time, but it seems a bit odd.
- While not related to Smash necessarily, the SNES controllers (and potentially a direct) were delayed by a month- maybe because of Smash? Since the SNES controllers are almost certainly going to be fully revealed along with more SNES games on Switch, maybe they wanted to show Geno and SMRPG at the same time? There's also Animal Crossing's release, which they may have wanted to keep in the same direct as a Smash character?
- The final, and most subjective reason... Byleth feels out of place in the first Fighter Pass. We have 4 3rd party characters from different companies, all completely new series to Smash... and then Byleth, the 8th Fire Emblem character in Smash. It'd make a lot more sense if, say, fighter #5 was meant to be 3rd party, and the SECOND fighter pass was meant to be almost entirely first party. (or at least have a few first parties rather than just one.)
All of that evidence might sound well and good, but it means nothing unless there's a good reason for them to swap the order of releases. Arguably, there are a few reasons that could work, but none of them are exactly rock solid.
- Sakurai saw the Cacomallow leak, and had to change plans because of it. This might seem like a "Nintendo would never do that over a leak," and while there isn't exactly a HUGE precedent for it, there is the "brave" codename being scrubbed from the files, as well as the WoL character slots being obscured and added onto. Obviously, changing some code to hide things like this is a lot less effort than swapping character order, but they have done something like this before.
- The reason this potentially makes sense is, say Doom Guy was meant to be Fighter #5, Byleth was meant to be #6, and Geno was meant to be #7. If they announced Doom Guy in December, showed his mii costumes shortly after, and those costumes confirmed 1/2 of the Cacomallow leak... we'd be waiting like 6 months before the official reveal of Geno, while knowing with 100% certainty that he was coming. That'd all but kill the hype and speculation for a lot of people. They swapped Byleth with Doomguy to reveal Doom later when they could tease Geno at the same time.
- Something went wrong with fighter #5, and they had to release SOMEBODY before the end of february- so they decided to delay #5 and expedite #6, so they'd have a bit more time to finish or work out bugs, or a bit more time to solve some copyright problems or something. This one is possible, but I don't see it as very likely due to all the unknowns. What could possibly cause them to delay a character that they'd already negotiated for?
- The Smash characters were swapped around for the same reason the SNES controllers were swapped around- If Geno was meant to be revealed for Smash alongside SMRPG on Switch, then maybe the delays with the SNES controllers caused Geno to go from #5 to #6? This one obviously assumes Geno was meant to be #5, which we don't have a lot of reason to believe thanks to Hero, but is possible.
What does this mean? idk you got me i just felt like typing this it was fun