Not available

I'd like to see some serious sh!t go down between Godzilla and Ghidorah

This is a great topic (upvoted)! You mentioned a lot of what I'm hoping for as well. 

Without a doubt we need some amazing areal shots of Rodan and Ghidorah. We also need to believe how much of a threat Ghidorah is, so seeing him dominate Godzilla I agree is a must. 

In terms of Godzilla vs. Kong, yeah I can see Kong being confident enough to run head on at Godzilla. That brawl is going to be incredible, I really can't wait to see that unfold on the big screen. 

Beyond those few points I too would like to see cameos and reference to other Toho monsters. Varan and Baragon could fit into the Hollywood mythos seeing as their origins and organic nature would make it easy to write them in, opposed to Gigan or Megalon. Although, I would LOVE a Legendary Gigan... I realize how unrealistic it is to assume he'll ever be included. Haha

///

I would love to see Mecha Godzilla be introduced into the series.

I'd like more realism chucked out the window in favor of the fantastical. Just like the slow progression into over-the-top insanity the Showa series went through. Or the Marvel Cinematic Universe.

Gman- I wouldn't mind that.

I'd like to see Ghidorah as an alien.  I'd like to see a large mix of new monsters as well as old.  Speaking of old, I'd like to see Varan, Destoroyah, Gigan, and maybe even Orga thrown in, and even though I am kind of finding him boring in the Toho movies nowadays, I really wouldn't mind seeing MechaGodzilla introduced at some point.  It would be neat to have a post credits scene that shows him under construction, teasing an upcoming battle.  I would also like to see some monsters that aren't necessarily Toho related, like Gorgo.  I think he could be a cool monster to see in a Godzilla film.  I think the Gargantuas would be neat to see in a Kong film.  As my want for an alien Ghidorah implies, I would like to see some alien involvement in the films.  Doesn't have to intelligent aliens, maybe just alien monsters. 

///

Let's see....

For Kong against Godzilla, I definitely wanna see the giant ape use his surprising amount of agility, speed, and creativity to make up for Godzilla's raw power and durability.

I also wanna see Mothra and Rodan have an aerial tussle, since the two look to be around the same size and could have interesting dogfights. Heck, have them both take to the skies against King Ghidorah!

I'd love to see a remake of Biollante, Destoroyah and Orga, maybe in a leter movie. I think it would be super cool if they where able to have Gigan take a part as a Pacific Rim Kaiju, and have him dominate the Jaegers sent against him.