the enemy monster would be something from our nightmares. Like the Hell beast from the Godzilla NES creepy pasta series.

godzilla attacks san Diego comic con while the comic con godzilla teaser is going on in Hall H.

I would make it very dark. Like the nolan batman series kind of dark. I would make it scary and very depressing.

No MUTOs.  Just Godzilla vs Man.  I would have a scene where Godzilla is nuked, but when the smoke is cleared, we realize that he is twice the size, with even stronger atomic breath.

The new pissed-off 700 foot Godzilla destroys entire cities, including Dubai, Hong Kong, Shanghai and, of course, Tokyo.  When he gets to America, he targets Miam.  The first landmark he comes to is a movie theatre showing Godzilla 1998.  He huffs and lets out an atomic blast never before seen that blows the fuck out of the theatre.  After the theatre is incinerated he hears cheers from thousands of onlooker.  But  before he can take a bow he is met by a new weapon which turns atomic energy in on itself, thereby causing Godzilla to implode.

As the credits roll we see hundreds of imploded Godzilla body parts slowly start to take form and grow.  The implosion didn't kill Godzilla, it made him multiply.... to be continued

I would introduce a very somber tone. I might throw a bot of a dark romance in there to but nothing heavy! I would include a new host of original monstrosities aswell!