After Ghidorahs defeat the world was mainly peaceful

Destroyahs had returned to deep hibernation in the core of a volcano

Mothra had not done much except help defeat some other Kaiju that the good Kaiju had discovered

Titanosaurus had just stayed asleep on his island,not doing much but resurfacing when he was disturbed

King Caesar was doing the same as Mothra,helping defeat other evil Kaiju

Rodan had gone into hibernation,Same as Destroyah and Titan,staying asleep in a volcano near Hawaii

Godzilla had been hunting and killing other Kaiju that didn't want to accept that he was alpha,some accepted that he was,a Muto,,Mothra larva,and others,though the creators of Ghidorah and some humans wouldn't accept that he was king,so they hatched a plan,the Alpha-A program

I'm thinking of making a sequel to this,watch out for it