Godzilla vs. Kong hinted that humanity may be aware of over a hundred Titans in the MonsterVerse at this point. In Godzilla: King of the Monsters, Monarch had knowledge of a much smaller number of Titans living on the planet, all of which they were monitoring through various outposts.
At the beginning of Godzilla: King of the Monsters, Mark Russell (Kyle Chandler) found out that Monarch had files on 17 different Titans that were scattered all over the planet. Of course, these included Godzilla, Kong, Ghidorah, Rodan, and Mothra. Over the course of the movie, audiences were introduced to four new Titans as well, which were Methuselah, Scylla, Behemoth, and a third member of the MUTO species. Plus, there were 11 more whose names were spotted on a monitor screen, but the monsters themselves never appeared on the screen. By the end of the movie, there were 20 confirmed Titans in the MonsterVerse.
Each of the monsters that Monarch knew about had a designated outpost build to contain or observe it, and all of these stations were related in some way to Titan activity. Maps indicated there were less than two dozen outposts on the planet, and that number corresponded rather accurately with the number of Titans on their radar at the time. That’s why it’s interesting that Godzilla vs. Kong labels the Kong containment facility on Skull Island as “Monarch Outpost #236”. That number means that the amount of Monarch outposts on Earth has skyrocketed in the five years that have passed since King Ghidorah’s defeat. Why would there be a need for Monarch to operate over 200 outposts? The obvious explanation would be that a multitude of Titans have been discovered in the aftermath of King of the Monsters.
This figure doesn’t mean that there are necessarily 236 Titans, considering that Skull Island hosts two Monarch facilities (the other being King of the Monsters’ Outpost #33). But, it does suggest that the number of known Titans has gone up quite a bit. Monarch wouldn’t need more than 200 outposts to observe 20 Titans.
As for how Monarch could have come across a hundred more between Godzilla: King of the Monsters and Godzilla vs. Kong, it’s worth noting that the previous installment did set up this possibility. When telling Mark about the 17 Titans, Serizawa made a point of saying, “and counting,” meaning Monarch knew more were out there, and that the number would keep going up as their research into the Titans continued. Also, Monarch beginning expeditions into the Hollow Earth tunnels surely sped up the process and led to more being found. There’s also the matter of King Ghidorah’s call. The monsters that answered it in the movie may not be the only Titans it reached. Others could have been stirred by the call, but didn’t reveal themselves until after the events of the movie.
As pointed out by King of the Monsters director Michael Dougherty, having so many Titans in the MonsterVerse will make it easy for later movies to introduce new Toho kaiju whenever the need arises, but there’s also one notable downside for Godzilla and Kong. More Titans means there will be more enemies looking to challenge them in the future.