Mecha-Godzilla

I personally can't see it working either. Mecha-G would ruin the (somewhat) believability that's been established in the MonsterVerse with G14 and KSI. True that the limits were really pushed in KotM (a little too much for me), but adding a ~400' machanical monster is just on a whole other level.

Also, world building is fine if it's done right, but I think that making GvK an all out "destroy all monsters" kaiju flick with ancient, genetically modified, or machanical monsters all going out at eachother would be a huge mistake. The title of the movie is Godzilla vs Kong, and as such I would love for it to be soley focused those two characters. Their emotions and motivations can't get through to the audience if there's more than just their battle going on at the same time, imo. I really don't want Mecha-G in the movie much at all, but I have a feeling that might not be the case.

The various Godzilla continuities have always strayed from their previously established tones. Godzilla '54 dove confidently into Godzilla fighting a three headed space monster on another planet. The Return of Godzilla's cold war, disaster movie feel eventually went into time travel and mechanical monsters based on technology from the future. Even the Kiryu Saga added straight up mysticism by its second film.

In light of this, I say let Godzilla vs. Kong go bonkers. Bonkers is fine--I just want a good bonkers movie in and of itself.

I agree that if they make it a "destroy all monsters" movie, it would flop and the Monsterverse would end. 

@KingSalomonMMIV

I don't know about mecha Godzilla woking either. Maybe GvK will have the same feel as KOTM, the only way they could keep the "believability" intact would drastically change Mecha G. But it could be fun though.

Mechagodzilla is an interesting choice for GvK, but I digress.

He could be a good thing if they go the of Pacific Rim. Make him slow and heavy, due to him being machine and Kong and Godzilla being faster due to them being natural.

I like it. It doesn't make much sense, sure, but Godzilla films never made sense, did they? A kaiju film universe like the Monsterverse shouldn't restrain itself to realism.