I looked at that article about Doomguy's inclusion and i didn't really read that carefully (So sorry on that one) but one thing i would suggest is making sure the representation isn't 2016/Eternal Doom heavy.
Mostly because of the art direction, not only with the classic Doom armor but also the look of the stage.
Considering the reputation and influence on level design and the Megawads, i feel like a UAC base would make sense if it had some classic Phobos in it and with Hell, the first games had a more versatile Hell version, as opposed to 2016's, 3's or even 64's Hell.
The new games can expand the gameplay but the classic designs are still iconic and even less "overdetailed" and colorfull/cartoony, along with what they represent too.
I remember making some medium post where i tried bringing up some suggestions for Doomguy in Smash and the idea was mostly exploring different games and going on a similar route to something like the mod MetaDoom.
Problem is, that post is so outdated, it was made before when spirits were announced, but released after that and i don't feel like making a follow up or editing the post, so anything that could have be seen as additions and more ideas are just previous posts i posted in this thread.
But basically, always start at the beginning then progress until the last entry.
Sometimes you can make literal combinations, like a Praetor suit that is even more classic and has a grey helmet.
Or "Mick Gordon noises" on Bobby Prince music.
Here's the post in question
https://medium.com/@bigfunnygun9000...eat-addition-for-smash-long-post-7c00b53022e6 which is old and outdated.
I've also made this about Hell's portrayal in Doom
https://medium.com/@bigfunnygun9000/another-post-about-hell-in-doom-c468af92b228 and as of right now, i noticed something that shouldn't be in there in the end and i tried editing it, so i'm not sure if it's gone but oh well.
I guess the console ports are a bit better at least although it won't really compare to the more options on a fanmade source port or even the more faithfull experiences.
Or the mods and fanmade content.
After all, since the beginning, they could have got in touch with some source port devs.
But even GZDoom isn't that perfect and i wish some other ports like PrBoom+ and Crispy Doom were brought up more times.
If anyone wants to be better at Doom, you can watch the PRO DOOM MONSTER STRATS video by Pordontae or most Decino's videos where he explains a lot of Doom stuff.
I'm curious about what the new trailer could include, like more about the monsters or the HUB.