so we have the backbone of what has occurred in our timeline of godzilla/ghostbusters events.
so now what?
well, let's address the time of departure for godzilla and friends. they disappeared in 1975, only to reappear in 1985, one year after the Gozer incident.
the question is: where were they?
the answer: they were evolving...
during the Heisei period of films (the period between 1984 and 1999, the kaiju learned a new trick; they learned about their kaiju essence, and how to transfer from one state of being into another state of being. it's kinda like matter transference, since matter can't be destroyed, it just changes states. the very essence of the kaiju escapes into the air, appearing much like a gold dust. this cosmic state of the kaiju directly relates to their cosmic beginnings as part of the whole. (see the beginning of time)
also, they learned how to transfer their essence to other things, such as other monsters as pure cosmic energy (rodan does this really well in godzilla vs mechagodzilla 2). this is key to what we're doing here, so we will assume that this become the standard for kaiju for this storyline.
so where do we go from here?
Gozer is back in our dimension because of the Dimension Tide weapon fired in 2001, but the entity is weak, and needs the souls of the dead to get its power back. over the next decade, gozer is able to regain power, nothing too significant for the entity to cause tremendous destruction, but enough to cause disruptions for the general populace. Gozer too begins to understand what is occurring with the kaiju, and realizes the only way that The Destructor will be successful in it's campaign of destruction is by becoming the most powerful entity on the cosmos.
so how does that happen?
lets assume that monster island is still the home for all the kaiju in the world. and with all the kaiju in the area, there is also all that untapped essence there. Gozer sends a Spectral Vortex over the whole island, siphoning off as much kaiju essence as possible.
the effect is that the ghosts around the world are becoming more powerful, harder to trap and eliminate. obviously, VSSZ catches on to this, and their agents begin to research why this is happening.
additionally, g-force is looking into monster island, and this giant vortex that is being held over the island. they begin taking some measurements, and it appears that the kaiju on the island and getting weaker and smaller.
where's the power going?
it's transferring to staypuft, the last and most recent form of the destructor. he's becoming more powerful, bigger, and possibly the king of the kaiju.
more to come