One of the secret kaiju in Godzilla reboot introduced audiences to a brand-new version of the iconic Toho monster, one that was understandably far removed from the 1998 version that ruined the character's reputation in Hollywood. And while the movie reboot aimed to give viewers a more grounded take on the monster, the film also opened up numerous possibilities for the future.
Shortly after Godzilla released, WB and Legendary announced plans to develop Godzilla's world into a full-fledged shared universe, which has since been officially named the MonsterVerse. One of the first things they did was announce a Godzilla sequel that would include Titans in Godzilla: King of the Monsters.
Related: Godzilla: King Of The Monsters Reveals A New Ghidorah Power?
In addition to showing off more of Godzilla himself, the two new Titans for the MonsterVerse. While it's unknown who those two new Titans are, specifically, it's been theorized that the crab-legged monster is Kumonga while the monster under the mountain is Anguirus. To make matters interesting, Dougherty revealed in a recent interview with CinemaToday Japan (via Gormaru Island) that Anguirus is one of his favorite monsters. The other two being MechaGodzilla and Biollante.
Furthermore, in the same interview, Dougherty said that if he could make another Godzilla movie (presumably Godzilla 3?), then he would certainly include Biollante and Gigan. Since we know for sure that one of the two secret Titans in Godzilla 2 isn't MechaGodzilla, and that Godzilla: King of the Monsters trailer.
Sure, this doesn't expressly confirm Anguirus for Godzilla: King of the Monsters, but it wouldn't be the first time that a director has said that he or she wanted to use a specific character in their movie, only for that same character to later show up in said movie. (This mostly happens with superhero films, but it's applicable here.) And since that there's already speculation Anguirus is in Godzilla: King of the Monsters, it stands to reason that the iconic monster is appearing in the new film.