(Was at work when this was posted, just saw the response notif)Its been outright stated Sakurai isn't the one who picks the characters.
I know this was said at the start, but seriously, look at the packs. I feel like "Nintendo" chose them, but it was Sakurai asking.
Persona 5 — Sakurai made very clear how much he adored that game. I don't think Nintendo said, "let's advertise this Sony exclusive game and franchise [Persona] as our first pack." This right off the bat said Sakurai had a say in things.
Dragon Quest — Not totally sure how important it was to him, but it's a cultural zeitgeist in Japan. Maybe this is more Nintendo based? Dragon Quest 11 would make gains, I suppose. This sounds the most "Nintendo forced."
Banjo Kazooie — This feels more to me like Sakurai taking fan wishes into account in the same way K.Rool was (heck, he even made clear that K.Rool was a Western addition). Think of this as a delayed Ballot release, I suppose.
Fatal Fury — 100% a Sakurai deal, like, that was a starting point to him even developing Smash. The showcase of Terry's was literally him gushing about Fatal Fury and the history about it, lol.
Fire Emblem — Which leads to Byleth. Sure, if they were the first to be released we'd be like, "okay, Nintendo, we see you," but being put at the end I kind of feel like it was heavily Sakurai involved. Especially since he's a massive Fire Emblem nerd.