Around the days of the Super Nintendo, Nintendo came to Sony asking if they could have a Nintendo based CD platform console. Around mid-production of this, Nintendo jumped ship for some dumb reason and went to Philips, which was doing okay at the time, but then they finished the console which was known as the Philips CD-I.
Now, the console Nintendo made with Sony 'kept going', and Sony eventually finished the first Playstation.
Essetionally, if it wasn't for Nintendo, Playstation wouldn't even 'be' here.
Now, am I saying Mario should be in? No. Can he be in? No. Do I want him in? Hell no.
But this story is more plausible for an add, than most of the 'reccomendations' on this forum.
Thats the thing though.
If Mario, one of the characters belonging to a company that eventually 'made' the Playstation won't get in
Then neither will Batman, Deadpool, Digimon, Goku, or any of the bad side ideas people have thrown out and tried to defend.
The fact that Nintendo jumped ship WITHOUT TELLING SONY caused a huge rivalry to be born. Sony wasn't even too keen on creating the console for Nintendo in the first place, but after they betrayed them without telling them, the Sony execs were like "THIS MEANS WAR. FINISH THE CONSOLE!"
The Playstation is purely a console of Vengeance.
Mario is more iconic then anyone on this roster, add him and he'll bring in 4x more sales.
Mario is only more iconic because him and his franchise have been milked for the past 30 years, so everyone knows who he is.