As I've said before, it's hard to call a monster movie "bad" when the very genre admits and even revels in its badness. Godzilla Vs. Mothra is considered by many Godzilla fans to be one of the better entries in the series. The story (such as it was) was reletively coherent up until the end, but the main event (Godzilla fighting Mothra) isn't worth the build-up.
We open with a terrible hurricane that is decimating a model town. Water pours everywhere, knocking down buildings but strangely leaving lampposts standing. During the cleanup after the storm, a humongous monster egg is found floating off shore. The enterprising villagers tow it to shore, and sell it to a money-grubbing entrepeneur, who figures it to be equal to 153,000 chicken eggs, and so pays fair market value of 900,000+ yen for it.
The business man wants to set up an incubator around the egg and sell tickets to see it until it hatches. What he plans to do with whatever eventually comes out of the egg is anybody's guess.
A pair of one-foot-tall girls shows up, begging the business man to give the egg back to Mothra. He of course refuses. The girls then hide in the woods until a reporter and his photographer show up, and then they try to enlist their help in getting the egg back. "The egg was washed away from Monster Island in a great storm," they say, and to back up that point we get a two minute recap of the egg falling into the sea during the storm, just in case we didn't understand what the girls meant.
The newspaper people try to convince the business man to give the egg back to Mothra, but they have no luck either, and so the girls disappear and go back to Monster Island rather abruptly.
Suddenly, Godzilla pops up out of nowhere (I guess he was washed ashore by the storm too and was just now coming around) and starts to wreak havoc on the Japanese countryside yet again.
The newspaper people decide that the only hope for the Japanese people is for them to go to Monster Island and try to get Mothra to come fight for them. This they do, and they return with the annoying little girls in tow to await the arrival of the winged one.
Meanwhile, the U.S. Navy fires about forty missile salvos at Godzilla (actually, it looks like they just fired the same two missiles forty times) and miss with every single shot. I really don't feel all that safe if the guys that are supposed to be defending our shores can't hit a 40 foot tall lizard at near point-blank range with eighty or so missiles.
The U.S. Navy and the Japanese Civil Defense Force fight Godzilla ineffectually with their two missiles and toy tanks until Mothra shows up. Mothra valiantly flies into battle, beating her mighty wings. The wind from the big moth's wings causes the big lizard to stagger but doesn't even ruffle the hair of the obligatory spectators who can't be standing too far off. Mothra flaps her wings for about five minutes, spits some yellow pollen on Godzilla, then dies. That's it. That's Godzilla vs. Mothra.
But wait, the movie isn't over! After about twenty minutes of painful singing by the tiny women (while Godzilla ambles around and gets shot at by the CDF some more), Mothra's egg hatches and two larva come out. By this time, Godzilla is wading towards an island not far off where some random kids are conveniently in danger. The larva follow Godzilla and spit at him. Their spit is apparently some web-like substance, and Godzilla flaps his arms ineffectually trying to ward it off. This goes on far longer than it should, until finally Godzilla falls into the ocean and (presumably) drowns. No idea how a monster that in every other Godzilla movie could live under water happens to drown in this movie, but that seems to be what is indicated. The two larva then swim triumphantly back to Monster Island, and the credits roll.
With a group of people, this might be good. Alone, it was just slow and boring. Godzilla fans may like it, but I didn't.
Scene to watch for: Godzilla getting his tail bitten.
Best line: "A good politician never lies."
Things that make you go "Huh?": The giant turtle on Monster Island.