I don't think it's ever been implied that more than one character from one series can't be in the same pass. Sure, you could say that it hasn't happened yet as the base of your reasoning... but then that's exactly what many people used in their 'spirits can't be fighters' reasoning.
Sure it's never implied. But that's where speculation and everything come in, like I always say there are no explicit rules aside from non-videogame characters can't get in. But we can assume a couple things here and there, and we do.
For example:
- Mii costumes added in as DLC around/after the time FP 2 was confirmed, aren't going to be in the DLC in FP 2. So we can expect that characters like Slime, Altair, Rabbids, etc won't become fighters in FP 2. This is entirely a "fan-rule", but it's still a pretty likely fan rule due to reasoning.
- Spirits added after FP 2 can't get upgraded. Same as above, and I wouldn't really expect RE characters to get in as fighters now.
Is it
technically possible? Yeah. Would I bet money on it? Not really. Most of the speculative side of Smash is just based off of logic rather than any hard official information.
Unless you also think that Slime, Resident Evil, Assassin's Creed aren't all deconfirmed. In which case, why?
So what you're saying is, even though FE gained 6 fighters in the course of two games, just getting 2 Mario characters, you know The Big Boss series of Nintendo, in the actual last wave of new Smash characters for a very long time, is unrealistic???
Excuse me, but how and why ?!?!
I mean if you travel back like 6 years in the past and say that within the next 2 Smash games, 6 FE fighters will get added into Smash I would still say that it's a bit on the unrealistic side. It happened. On the other hand, most of the FE characters that got added were clones/semiclones which totaled up to 3 unique characters rather than 6. If we count all the Mario characters added since Smash 4 we have around 4 completely unique characters comparatively.
Like I said, Walugi and Geno can absolutely happen together, but I wouldn't put my hopes in those odds. I wouldn't really say Byleth was likely for FP 1 either, and I was wrong about that.
Just the fact that "Mario" is a "big" Nintendo series isn't really enough to say that it's getting 2 characters. Especially considering that they haven't really shown off a severe bias towards Mario in Smash beforehand, so it's a weird implication to suggest that they would
now. And besides we all know that they value the primary Mario cast far more than the spin-off cast as well, as long as they get their Mario mainstays in Smash, they seem content.
Going by your logic we could assume that FP 2 is:
-Geno (because Mario is big)
-Waluigi (because Mario is big)
-2 Pokemon characters (because haha Pokemon go brrr)
-2 Zelda characters (because we all know that BOTW 2 will be huge and their big game next year)
Is it possible? Yeah. Is it
LIKELY? I
personally would say that at most each of these series
could get 1 fighter.