Despite Godzilla vs Biollante being one of the most expensive films made at the time, the movie lost a lot of revenue and it was thought that it was because the audience didn't like the new monster. Another cause was that the film was competing against Back To The Future Part II, so it was thought that the audience wanted stories about time travel. So they went back to look for a more iconic monster in the next movie and that would be Godzilla's arch-nemesis, King Ghidorah.
Originally, TOHO wanted to remake King Kong vs Godzilla, but they couldn't afford the rights to Kong from Turner Entertainment. So instead of using Kong, TOHO thought that they found a loop-hole and was going to use Mechani-Kong, but Turner Entertainment once again told them it was too similar and asked for the same ridiculously expensive amount just to use Kong or any likeness of him.
Godzilla vs King Ghidorah was seen under a controversial light because of the economic tension between USA and Japan and the movie's fictional depiction of WWII. Director, Kazuki Omori, denied these allegations saying that the American extras in the movie were happy about being squashed by Godzilla. However, Ishiro Honda (the director of Gojira) also criticized Omori saying that the scene was going too far. Entertainment Tonight scrutinized the film being in very poor taste that would hurt the American-Japanese relations.
When time travelers from the year 2204 claim to have arrived to warn 1992 Japan about Godzilla, book writer, Kenichiro Terasawa, psychic, Mikki Saegusa, and Professor Mazaki will soon discover that the time travelers have an ulterior motive in using King Ghidorah to force Japan into a surrender and force their computers instead.
I can see how Godzilla vs King Ghidorah would be controversial at the time. The movie is very anti-America. Now, it isn't as controversial as it was in the 90's and I mostly see it for what it is. It's just a Godzilla film with a lot of sci-fi elements. The problems I really have with this movie is that the special effects are sub-par at best and so is the acting. The special effects looks really cheap and the green screen effect makes people and objects look like paper cut outs when in front of the camera. The acting even sounds really bad at times and it makes me want to just cringe. This low quality of special effects and poor acting becomes a reoccurring problem through out the rest of the 90's movies. While it may have been passable back then, it didn't age very well over time and no longer passable now.
The story was also kind of lacking. I love the Back To The Future movies, but the reason is because of the movie's characters are like-able and the story stayed consistent. The time travel story in Godzilla vs King Ghidorah did not really fit in with the more serious tone that the first two movies had and didn't stay consistent. For instance, the time travelers first reason to traveling back in time was to warn Japan about their imminent fate of being destroyed by Godzilla. After getting rid of what they believed was Godzilla before he mutated, Emmy leaves behind these small bats called Dorats to be turned into King Ghidorah. When they arrive back to their present time, Emmy leaves her comrades in the time machine because she was upset that they betrayed Japan. To push it further, she even warns Terasawa and reveals that Godzilla never destroyed Japan in the future and instead only helped Japan become the next world power. Which means that she had to have known about the plan from her comrades long before they even first arrived in the present. She was even the one that left the Dorats to turn into King Ghidorah in the first place and she was even asked, "Where are the Dorats?" and she stayed silent. Wasn't it established before the movie began that Japan was actually destroyed in the future? Then, what was the point of stating that Godzilla never destroyed Japan? The story is very convoluted and makes no sense what-so-ever.
King Ghidorah looks awesome with a more up to date look that becomes the main staple of recognition by fans. What was cooler was the Mecha-King Ghidorah that appears at the end of the movie. This cyborg does not come with just armor and an extra head, it comes with all of this other stuff that grapples Godzilla and sends jolts of electricity into Godzilla paralyzing him. While it does play a crucial role of defeating Godzilla, Mecha-King Ghidorah is also the precursor to another one of Godzilla's mechanical foes in Godzilla vs MechaGodzilla II. Mecha-King Ghidorah is another one of those "one time" monsters where you see it in one movie and it never comes back again, which I am okay with.
What was once controversial, isn't as controversial anymore and you can either see passed it or not. This does not quite excuse the movie for having such a lousy story and horrible acting. Give it a watch only if you are still curious, but this one I recommend just skipping.