Just to cut to the chase, here's the list.
Mortal Kombat - 80 million
Super Smash Bros. - 72.39 million
Tekken - 54 million+
Street Fighter - 49 million
Soul Calibur* - 17 million
Dead or Alive* - 11.7 million
Marvel vs Capcom - 10 million
Virtua Fighter* - 5.5 million
Read more: https://www.tweaktown.com/news/91528/mortal-kombat-hits-80-million-sales-heres-how-it-stacks-up-against-competition/index.html
Yeah, compared to Street Fighter, color me surprised BIG TIME. Though I guess when in 2011, you're the big regular fighting franchise that tried to bring in newcomers (as I said, by popularizing modes and aspects found in what were considered licensed "shovelware fighters" from the PS2/GCN era) bound to happen.
And keep in mind, this is the only series on that list that after a certain point, doesn't release in Japan, the home of the fighting game genre (the movies are allowed though, even the 2021 film that had Hiroyuki Sanada).