Fire Emblem is a series with a very fluid cast. In a series that changes characters with each game, it makes sense to pick from the newest game. Same with Pokemon, though I don't think we should dismiss Mewtwo quite so soon. With Rosalina, she's (pardon the pun) a rising star in the Mario series, and offered, like Robin, something that her "competition" could not. Sakurai could have very easily thought of Toad as nothing but moveset fodder and Bowser Jr. as a smaller Bowser clone, whereas he could give Rosalina a puppeteer moveset.
And just as easily he could've thought of Rosalina as a bigger Peach clone, and give Toad or Bowser Jr or Waluigi or Paper Mario a unique moveset, they're all feasible. Yes, Rosalina is a "rising star", but when was the last time Sakurai picked a rising star above an individual established, more popular, more prevalent star for an original moveset?
I'm also not dismissing Mewtwo, I'm just saying he wasn't given priority over a recent newcomer.
And yes, it does make sense to pick from the newest FE game, but that's not what Sakurai did in Melee (understandably), and in Brawl he went to IS and they suggested the character from the newest game. He wasn't decided on Ike beforehand, and still attempted to include Roy, but this time it's like he didn't even give any title other than Awakening a chance for inclusion.
If it was just FE that he was on a recent recency bent it wouldn't be enough to judge other inclusions on, but let's look at the new series included so far: AC (counting it as new), Wii Fit, Punch-Out, Mii, and probably RH and Xenoblade. All series with post-Brawl impact. And the characters from established series came from Galaxy/3D World, Uprising, X/Y, and Awakening, all titles post-Brawl or primarily post-Brawl. You have to admit that including K. Rool would be breaking the precedent that seems to be set here.
It's not impossible for sure, but when you do have feasible, popular, importance characters in the series who
do fit under this umbrella, it seems unlikely Sakurai would choose to venture outside it.
Donkey Kong Country has kept the same sort of cast since its inception, generally. K. Rool has a big part in most of them, barring the two most recent. And even then, it's not like Dixie's a "rising star," as she basically is the same as when she was playable before, unlike Rosalina's ever-expanding appearances. And Cranky's already disconfirmed.
Hence, despite being in one more (possibly too recent) recent game than K. Rool has, I think K. Rool has an edge over Dixie.
But you're giving all the DKCs the same amount of importance and merit as far as representation in this game goes. That's not what Sakurai has been doing with the other series, and it stands to reason he wouldn't with this one either, especially since the two most recent have made the largest splash for the series since DK64. If all the titles were on equal footing, I'd agree that K. Rool does have more in his favour (though they'd still be close), but they aren't.
I fully acknowledge that Dixie can be made unique in a sort of Millia-type style, for example, but I just feel that, like with Robin, K. Rool would just "jump out" at Sakurai faster for being more unique. The option for semi-clone K. Rool doesn't really even exist. The closest people can make is arguably Dedede, but even that's a large stretch.
If a character we all thought would be a semi-clone at best managed to jump out at Sakurai, it's not like we can really predict what will and won't catch his attention. Robin only looked so unique in comparison to Chrom, but Dixie isn't in Chrom's position, she can legitimately be made original with little effort and minimal overlap with Diddy. Plus, we're assuming here that Sakurai would try Dixie first then opt for K. Rool, going by the Chrom and Robin comparison, but that's just it, an assumption. Chances are if Sakurai does try to include Dixie he'll do his best to find her unique qualities, of which she's not as limited as Chrom. Especially since Chrom was found redundant after both Marth
and Ike, without one of them Sakurai probably would've given him the general playstyle of the other - or at least something close to it, but with Dixie there's only Diddy and there's less redundancy.
And Dixie could also make for a semi-clone unlike K. Rool, which is a point in her favour.
She's really only made one high profile appearance since Brawl, and considering a "Tropical Freeze" character wasn't listed on the Sal Leak despite "X and Y" being on there may mean that it did come too late to matter. Maybe. Fair point with Roy though.
He didn't list a DK character at all though. For all we know it's entirely possible Sakurai never intended to include an original DK character this time, but in the period of padding the roster, which DK character is going to make for the best clone? Like you said, not K. Rool.
Plus Little Mac, Greninja, Palutena and Shulk only made one high profile appearance since Brawl as well when they were chosen.
The thing here is timing. Pyrosphere was announced really early on, but there still isn't a DK stage, barring Jungle Japes. And even then, I'd say it'd point more to K. Rool, as it shows that Sakurai is aware of him still. I can't see Dixie playable with a K. Rool stage boss. And in regards to the other thing, I view it more as each new character getting a home stage, as opposed to just using new game stages. Arena Ferox is where Lucina is first fought, with Robin there too. Greninja has Lumiose City (where the Professor who gives it to you lives) and the Kalos League (essentially the last hoo-rah to use Greninja in). Most notably, Rosalina has a Galaxy stage, and not a 3D World stage. Hence, I think if K. Rool were playable, they'd use the Galleon due to it being his home stage.
Or... they were chosen because they're iconic locations within the games...
You're trying too hard to connect the dots here, new stages aren't indicators of new characters unless it's from a new series. And not even then all the time. Did you think we wouldn't get a Galaxy stage? We got a Sunshine stage last time, and a 64 stage before that. Lumiose City is one of the most iconic locations in the game, and the Elite Four is one of the most iconic locations in the whole series, they have nothing to do with Greninja specifically. Arena Ferox would be able to be linked to any Awakening character with a chance tbh. Stages are generally just chosen to represent the new games of the series.
It's pretty inevitable we'll be getting a stage based on one of the new DKC games... not that that means anything specifically as far as characters go. If we do get Gangplank Galleon as a stage, yeah it's pretty probable K. Rool would be involved, but not necessarily as a playable character. And getting Gangplank Galleon in the first place is just a guess.
Visually, they're all brown-furred primates, like how Marth, Ike and Chrom were blue-haired swordsmen. Like Ike, DK may be more visually large, but the similarity is still there when a more distinct alternative (K. Rool/Robin) can be made.
It wasn't the colour of hair that got Chrom excluded though, it was the lack of diversity Sakurai found in his playstyle.
Also, we still have three blue-haired sword-wielders from FE, if it was a problem... we wouldn't.
Some of them didn't exist until then. Namely, these are Wii Fit Trainer, Rosalina, Greninja, Robin, and Lucina (Chorus Kids and Shulk too, if you consider the leak). Pac-Man and Mega Man don't take from their recent appearances and are third party. Miis and Villager were considered, but Sakurai went back and added them this time. Really, the only newcomers that got more important post-Brawl were Little Mac and Palutena, and they had tons of fan popularity anyway.
Exactly, look at all the character that didn't exist before Brawl that have now wound up included. Look at the characters that got important post-Brawl that have wound up included.
Now look at the characters who existed before but didn't get any more important post-Brawl and see how many of them are included. None. Every single one had some kind of notable impact post-Brawl.
And I'm not including third-parties because they're in different situations here.
What it boils down to is the problem doesn't lie with K. Rool as a character, the problem lies with Sakurai focusing on a time period in which K. Rool didn't stand out or make any waves, yet another character in his series does. We haven't seen the entire roster yet obv, but there's a very good reason to believe all the Nintendo characters will be those that had an impact post-Brawl, all nine newcomers and the remaining two "leaked" ones all have. You can argue K. Rool's positives all you want, and I'd agree with you on them, but it seems like arguing for a character outside the boundary of what Sakurai is even considering this time around.
If we had gotten a retro... or a character who made their impact primarily pre-Brawl, I'd be right with you think K. Rool stood the best chance, but there's a point when you have to look at the landscape of what we've gotten, see that it's been unilaterally in one direction as far as Nintendo characters go, and reevaluate. I could be wrong, sure, but given the precedent it makes sense to presume that's how the rest of the roster will pan out as well - in favour of the recent.