I'm of the opinion that it's better not to "expect" anything. Not necessarily in the way of "lmao Sakurai is unpredictable, he's going to add a bunch of wacky characters!", but rather that we cannot pretend we know how the team chooses what characters to incorporate.
Before Ultimate's official E3 reveal, and even after it, I was convinced I knew what we'd be seeing, characters with prominent games on the Wii U, such as Elma, Captain Toad, and so forth, just like how 3DS / Wii U's roster focused on the Wii era (with a little bit of 3DS thrown in too). I expected the majority (if not all) of Wii U's roster to return, alongside Ice Climbers and MAYBE Wolf and Snake. I know I wasn't alone in that thought process.
We, as a community, tend to get stuck on an idea and then stick to it until it's proven or disproven. If it's proven, we brag about how we "guessed right" and use that as an example to push other concepts. If disproven, we either throw a fit that they'd introduce / ignore our option, or use it, again, as leverage to push other concepts.
My point, in my tired, caffeine-powered ramblings above, is that I think it's for the better that people show support for characters they want rather than attempt to predict the design ideologies of multiple different developers (because, no, while Sakurai works much harder than he needs to on this game and very well deserves some applause for the effort he puts into the series, he is not the only person dedicated to making this game the best it can be and the majority of the effort put in goes thankless or is credited to Sakurai).
Think about it. Ignoring rumors and leaks, the only addition I think could argued to be a lock would be Inklings, because of course they'd be in, they're Nintendo's big new IP that's taking the world by storm.
- While people were fairly positive Ice Climbers would come back, and to an extent Wolf, you cannot tell me anyone expected every single character, including Pokemon Trainer, Young Link, and Pichu, to return.
- Snake, despite being popular, had everyone thinking a big nope because Konami's evil or something.
- Ridley, a popular choice who was discounted by the team for 3DS / Wii U due to balancing / "too big", was then discounted by most fans because of that stance.
- Look me in the eyes and tell me, before E3, that people would be OK with multiple new clones with minimal differences. That people wouldn't throw fits over Chrom, Dark Samus, or Daisy, all being complete clones like Lucina or Dark Pit.
- Before Verge leaked Ridley and Simon, everyone had their eyes on Bomberman big time, as he was "the likeliest" second Konami character, assuming Konami even wanted to play nice. Don't forget Richter as a clone, something so unexpected even after the leak.
- King K. Rool. Just... King K. Rool. He is, by all means, a dead character. He hasn't had a prominent role in the DK series since Jungle Climber (a spin-off, nonetheless) on the DS in 2007 well before Brawl released. The only other appearance beyond trophies in Smash was as part of an ensemble of unlockable characters in a Mario sports game a year later. OVER TEN YEARS since he's been even slightly relevant. The only thing keeping him alive was Smash fans wanting him, and DK fans hoping for his return in some form. It's not like K. Rool is a prominent retro character like Duck Hunt or Pit that the team digs up from a pile of Famicom games and decides to revamp for fun, he's a character who Nintendo felt no need to push. He was added simply because he was so highly requested. Nobody can honestly tell me "well I expected K. Rool and you're just overgeneralizing" because there was literally no precedent or alternate reason to add K. Rool to Ultimate beyond fan support, and we all know that.
I think it's pointless to put so much faith into predictions for Smash, especially when it's just surface-level speculation without any thought put into the actual development of a game. I think it's much better to use outlets like social media, art, music, videos, essays, and so on to support a character rather than things like "well, due to sales, relevance during development time, and balance between franchise representation and a potentially unique moveset (nothing annoys me more than saying a character could be unique without actually showing how), I can say for certain we'll see this character otherwise I'll sacrifice my pet cat".
Where was I going with this again?
Oh yeah, congrats
Opossum
on getting your chance this time!