There have been multiple interpretations of how Kaiju reproduce. In Legendary’s Godzilla, the MUTO were able to breed the old fashioned way with a male and female. There have also been examples of Kaiju breeding asexually such as Zilla, Godzilla Earth, and Shin Godzilla, etc. Personally, I find asexual reproduction to be more plausible for Kaiju because if they bred with a male and female, they would be so big that their bodies would be crushed to death by their combined weight. I will be exploring Kaiju asexual reproduction in my story, but the method in which it is done will be most unexpected.