After reading both of your responses, I decided to take some time off to formulate what I wanted to change with my image in response to your guys' feedback, and now I believe I have something mostly satisfactory here. I'll go over my changes under the image:
-So the first thing I decided to change was moving Noah to base game after being suggested multiple times to do so. I made this image with the assumption of a 2024-2025 release for Smash 6, but XC3 officially getting an August release date is what finally pushed me to put him in the base game section. I also cut Rock Howard as an echo (unfortunately) in favor of having Mio as Noah's echo, since I read about how both protagonists can use each others' weapons, and because of this I imagine they will both be designed as Echoes to each other, similar to Simon and Richter in Ultimate. Not much else to say here other than that I'm overriding Raven Beak with the XC3 protags for the time being, after being convinced about his difficulties as a Smash candidate.
-Also, screw it, I'm putting Bandana Dee as the other "demand fighter". This is still subject to change as I'm still not 100% confident in a fourth Kirby character though, especially since along with Waluigi, this would basically be Sakurai caving in twice over (perhaps Sylux can clutch this spot last minute if he's in Prime 4).
-I'm sticking with Diskun for now since I can't really think of any other surprise legacy choices that would fit here. Color TV-Game has the same Japan-only issue (and is an Assist Trophy), 8-Bit Mario would feel extremely redundant, anything Nintendo LABO related wouldn't feel right since LABO kind of just came and went, and Harry from Teleroboxer...was actually someone I seriously considered, but I'm not sure Nintendo would want anything Virtual Boy-related as a big "legacy" representative for them, given how five games in and counting, there's barely anything from Nintendo's VB titles in Smash.
...maybe Mach Rider?
-I swapped Iori and Zero. I was initially hesitant about Iori as DLC, but upon further research, there's actually a lot of KOF and KOF-associated content not in Ultimate at the moment, so I see no harm in having him as DLC like what you guys suggested. Moving Zero back was also easy. Even though there's no visible room for it on here, I think Capcom would want a new IP of theirs to be DLC instead of a second Mega Man character.
-Decided to move around Greninja and Incineroar, upon multiple suggestions to do so. Though on the subject of veterans, I'm standing by my decision to cut Roy (and Chrom), mainly on the grounds that the former isn't too popular in his home series, was only included in Melee to promote his then-upcoming game, and then missed both Brawl and Smash 4's base game. I can't help but feel that if Smash 6 makes cuts, then it's finally time to retire the boy. As for Chrom, maybe he could be repurposed as an Ike echo if he proved popular enough to stay, but I'm unsure since his Ultimate inclusion felt very much like an afterthought anyway.
-Dropping Noah from the DLC section allowed me to add in one last prediction I'm pretty confident in, that being a slot for a Namco DLC character. I picked
Lloyd, the
Chosen Undead, and
Nightmare as the top three frontrunners for this slot; Lloyd because of the popularity of the Tales series along with him being a requested character since Brawl, the Chosen Undead because of the extreme popularity of Dark Souls and its associated series, and Nightmare because he's a fighting game character who's also a swordsman,
perfect for Sakurai! Though for a more serious reason, Soul Calibur does have direct history with Nintendo, thanks to Link being a guest fighter in the GCN version of Soul Calibur II.
-Changed the Atlus placeholder into just a Persona placeholder upon dream1ng's suggestion. That, and the fact that if the gap between Persona 4 and 5 is any indication, we're due for Persona 6 in roughly 2-3 years from now. While Garteam does have a point about Joker making a splash on Smash's community, knowing Atlus, they probably won't care and will want to push Persona 6 as the next big thing, and I imagine that the P6 protagonist will play very similar anyway, other than having a different main Persona replacing Arsene,
-Finally, I turned Doomguy's slot into a general placeholder slot for a Microsoft character, of which I see the aforementioned Doomguy as a potential frontrunner, along with
Master Chief and
Crash Bandicoot when the Activision buyout is finalized for the latter.
Also, I'm still sticking with Kris for the time being, but if the next Smash comes out and Deltarune still shows no indication of being remotely done, I'll probably take him off and replace him with someone else.
Apologies for taking a while to respond to the both of you. Even though this took me a bit, don't let that deter you from giving more in-depth feedback if you want to.