Alright, I know this is going to be crazy, but I have to do it...
Kratos (God of War)
Who is Kratos?
Kratos is main protagonist of Playstation series "God of War", made by Santa Monica Studios and published by Sony Interactive Entertainment. His first game was released on Playstation 2 in March 22, 2005 that sold many copies since it's launch.
He is a demigod or god (From now on) known as "Ghost of Sparta", who has vendetta against the Gods, who mistreated him. However, he started to kill them brutally without mercy and he was even responsible for Greece's destruction at end of GoW 3, which it led him to move to Scandinavia.
During the events of GoW (2018), he raised his child known as "Atreus" and he treated him nicely like "Father and son". Also, Kratos started to kill the Norse gods, who also Kratos had vendetta for.
He was a son of Callisto and Zeus and he was Lysandra's former husband and Faye's former husband I guess... (I didn't played the God of War 2018, but I played God of War 3). He had two children: His son Atreus and his daughter Calliope, who were his children.
Kratos is no-brainer pick, since he is extremely iconic and he is flagship mascot of Playstation, which it led him popularity worldwide. He was even important for gaming history, especially Sony's. He is no stranger for crossover, since he appeared in Mortal Kombat 9, Fortnite and he appeared in Playstation Allstars Battle Royale in 2012 as Playable Character.
"How he could work?" + Aesthetics
You know, despite he is too brutal, he can really fight, since he was playable in PSABR and we could manage to make him playable in SMS without any issues.
First, he could heavyweight character, who doesn't have any movement options. His playstyle is "Rushdown" because of the God of War gameplay.
His moveset would be based on God of War games, like he could pull out his two blades or even his leviathan axe to fight. However, his moveset would be also combo-based, since he could make huge amount of combos while pressing or mashing the buttons.
He could have final Smash based on scene from "Father and Son", where he attacks the opponents while the arrows fly straight at them. This FS instantly KOes the opponents (From 1 to 3).
Kratos would have some gimmick in Smash, which it would be based on God of War gameplay, like combo-style gameplay, which like I mentioned earlier, pressing or mashing the buttons.
He would alsa have a "rage" like gimmick that would be similar to Kazuya's rage.
His design will be based on modern Incarnation of Kratos, but he could have his old design as one of his alternates. He would be voiced by current actor and his one of taunts would reference his son Atreus.
Why Kratos in Smash?
Well, Kratos should definitely join smash from scratch, because he is one of most iconic Playstation characters and he is a flagship mascot for Playstation like I said earlier. Also, he could be a new M-Rated character in Smash from Scratch, but we can tone it down and reduce his brutality in this game.
Also, the upcoming GoW: Ragnarok game, which it was released in late 2022, which it would spice up it's inclusion in Smash from Scratch. Speaking of new game, there is going to be a TV series based on it on Amazon Prime video.
Despite he didn't appeared on Nintendo Console, he still has a chance and nothing will stop from joining the roster. Also his inclusion is worthy since imagine Mario meeting Kratos in reveal trailer.
One last reason would be, that he would be surprising choice for Smash reboot, which it would make any fan shock when Kratos was shown in smash via reveal cinematic trailer or gameplay trailer.