You can unlock Galactus as a playable character by earning 30,000 points on your player card. Alternately, veterans of the series with a save file from Marvel vs. Capcom 3: Fate of Two Worlds (2011) will have Galactus automatically unlocked.
This video game takes place in the Earth-30847 of the Marvel Comics multiverse, together with The Punisher (1993), X-Men: Children of the Atom (1994), X-Men: Mutant Apocalypse (1994), Marvel Super Heroes (1995), Marvel Super Heroes in War of the Gems (1996), X-Men vs. Street Fighter (1996), Marvel Super Heroes vs. Street Fighter (1997), Marvel vs. Capcom: Clash of Super Heroes (1998), Marvel vs. Capcom 2: New Age of Heroes (2000), Marvel vs. Capcom 3: Fate of Two Worlds (2011) and Marvel vs. Capcom: Infinite (2017).
When Spider-Man defeats Firebrand, he says, "You know, you sort of look like the guy who ruined my marriage," a nod to the infamous comic book story "One More Day," in which Mephisto erased Peter and Mary Jane's marriage.