He has 4 appearances in this trailer alone.
I think Inkling is the only other choice for more marketed character than K. Rool. Sure, he's a deeper cut than Inkling or Isabelle for example, but Nintendo's trying to push the DK brand heavily and letting everyone know that King K. Rool is a big deal via Smash is a brilliant way of keeping him in the public consciousness during this drought of no DK games
Well other than the character's own trailer, which obviously is to market that specific character, showing up in other trailers is usually more because the character is thematically relevant to what's happening than to necessarily push the character.
Like, K. Rool showed up in the Banjo trailer because it was themed around a Rare reunion. He showed up in the Kencineroar trailer because they briefly show other boxers. So past a character's own trailer, I'm not sure how significant subsequent trailer appearances are.
I think order and location are a bit more important than quantity of trailer appearances, because that dictates how long they'll be part of promotion, and how many eyes will be watching their reveal (usually more at E3). Some veterans appear in trailers more than some newcomers, it doesn't mean they're being promoted more heavily.
That's what happens when you don't have a new game for 10 years. K. Rool's not going to magically appear in a non-DK game. The only DK characters to appear in Mario spinoffs are DK and Diddy and even Diddy's appearances are spotty. Mario Kart Tour does have Dixie and Funky though, but still no Cranky. The point is to keep the character relevant during this drought by keeping him in the public consciousness of being in a 30M selling game. Feel free to disagree, but that's my take
but they're not even doing that. k rool hasn't gotten anything whatsoever since smash and that game has pretty obscure and irrelevant character picks for the hell of it
I don't think Smash brought K. Rool back to keep him relevant for some greater purpose, nor do I think he was picked "for the hell of it". He was just a character who performed very very well on the Smash ballot and so they decided to add him. And it probably helped that DK as a series was still going, but I don't think there was some grand design besides him being a very popular fanbase pick.
I feel like it's a result of Nintendo being hyperfocused on gameplay functionality above all else. HAL manages the Kirby brand mostly by themselves so Nintendo doesn't intervene. But DK is an EAD/EPD IP despite being handled by Rare for the better part of a decade, so when it "came home," so to speak, Nintendo kept trying to tweak it on the margins to fit their vision of a gameplay-driven platformer (which is why the Tiki enemies all have obvious "you can touch this part, but not that part" designs). But now in an era where Nintendo is trying to become the video game equivalent of Disney, and turn their characters into marketable merchandise mascots, it seems completely counter-intuitive to hold onto this idea going forward. I'm a grown ass man who will buy K. Rool merchandise if you let me, Nintendo!
I agree that EPD has a streamlined approach to character inclusion, where they don't commonly include superfluous faces that don't serve some aspect of the gameplay. But it's also not
so exclusive that they can't tie an inessential gameplay-wise but core character to some aspect of the game so that they still serve the design.
I mean, it's not like Balloon World in Odyssey needed Luigi as the host, but he's Luigi and he didn't have any other role in the game, so there he is. In AC, Resetti's old function was lost with autosave, but he was a fairly prominent character, so they just gave him a completely new function gameplay-wise.
In Jungle Beat, there were small generic chimps who would guide you forward and help you swing from place to place, and dance at the end of the level with DK, and with minor level tweaks (but no fundamental gameplay changes) those easily could've alternated between Diddy/Dixie/Tiny/etc following him & jumping to certain areas or re-appearing at various points in the level (the bonus levels with tons could stay generic).
And that would've required slightly different design of some parts of some levels, but there were sections where DK rode a giant wildebeest, barrelling through obstacles, and there's no reason that couldn't have been Rambi. Same with the orca and Enguarde. There were flying squirrels you could hold onto and gradually float down, there's no reason that couldn't have been Expresso. Same with the birds that carried you upward and Squawks. They had bee enemies, there's no reason they couldn't have been zingers. There are weird gooey launching pads that could've just been barrel cannons.
There were gameplay elements that easily could've been covered by existing, popular elements. Incorporating that stuff wouldn't have changed its gameplay at all. It's not that there was no room for it, in some instances Jungle Beat literally reuses DKC ideas without the DKC characters. It seems deliberate that they stripped away all DKC faces, minus DK himself.
Honestly to me it just seems like more of EPD/EAD's disregard for things they didn't create. Which, thankfully, is loosening as of late.