A lot of this arguing is rather silly, and pretty pointless at this point in time. The only concrete thing we know about DLC post Fighters pass is that Sakurai wants to please the fans. That alone says something as well, as fans of the series would like first party characters. The best course of action from this point forward is to do a mix of characters rather than focusing fully on 1st or 3rd party. Keeping your current audience happy is just as important as trying to bring new people in.
This fanbase really needs to stop trying to predict Sakurai as he's proven time and time again that he's not going to go the way the fanbase as a whole expects him to and even this Fighter Pass is a very great example of that.
Honestly, when it comes to Super Smash Bros. fans, if you ask any one fan to give their top 5 most wanted characters, or even their top most wanted character, chances are you'll get a fairly even mix of 1st/2nd Party and 3rd Party..like take me for example, my Top 5 characters are..
- Sora from
Kingdom Hearts (3rd Party, Disney)
- Rex & Pyra from
Xenoblade Chronicles 2 (2nd Party, Monolith Soft)
- Byleth from
Fire Emblem Three Houses (2nd Party, Intelligent Systems)
- Zero from
Mega Man Zero (3rd Party, Capcom)
- 2B from
NieR Automata (3rd Party, Square-Enix)
As you can see, its a fairly even mixture of 1st/2nd Party & 3rd Party characters.
Any hypothetical first party DLC wouldn't be expected to carry a hype cycle to begin with. They would be released alongside a more popular 3rd party like Lucas, Roy, & Corrin all were because Sakurai isn't an idiot and would plan when to release said 1st for maximum effect. The main concern with the 1st parties is a question of whether or not Sakurai cares enough to bother making 1st DLC and aside from Rex who the man publicly endorsed in a Smash direct, I can't think of a 1st party who'd catch his eye:
-Arms and Astral Chain are too new to expect a character.
-Sakurai's got a pretty good pulse on the community so he probably knows Byleth/Edlegard would produce severe anti-hype among non-FE fans.
-The second wave of DLC has probably already been decided now which severely hurts a Gen 8 Pokemon (though its Pokemon so its still in the running by default).
-Agent 8 is completely redundant with Inkling around.
-In the game where Sakurai explicitly noted that the ballot played a big factor in terms of deciding the roster, the final 1st party non-echo newcomer chosen after the two ballot favorites, the new Nintendo all stars, and the obligatory Pokémon was...a generic Mario enemy literally nobody asked for. That's a pretty damning indictment for the prospects of pretty much every pre-Switch 1st party if you think about it. Even Waluigi, for all the fanfare he has around him now, hardly feels like a character Sakurai himself particularly cares about considering that Sakurai has known about his fan demand even back during the Smash 4 days and Plant still won out over him.
ARMS is no longer 'too new' and we don't know if the characters have already been decided upon yet or not, meaning we can't say anything is too new yet. The 'too new' comment was only relevant to the original Fighters Pass, as all of those characters were decided upon before release, but these new DLC characters sound like they were not originally planned on and likely are being done due to the popularity of both Super Smash Bros. Ultimate and the Fighters Pass, meaning anyone is essentially fair game now.
- I don't think it matter much if someone wouldn't be recieved well from non-fans of that series..
- We don't know if its been decided upon yet and Pokémon Sword/Shield were announced before this, so Sakurai could easily have had a Greninja moment where he picked a character or set a spot for a Pokémon.
- Octoling could be an Echo Fighter. Since this isn't the Fighters Pass, it means Echo Fighter DLC is possible (likely at a cheaper price)
- We don't know if Sakurai decided to pick all characters from the Ballot..its possible that Sakurai just wanted an oddball, random pick..since most of the time he includes at least one.