Sending Godzilla through time did free (for a time) the 20th Century from his threatening tread. As it turned out Godzilla traveled to the distant past, to a time when dinosaurs ruled the Earth, a time when Godzilla, still recovering his true size thanks to the application of Pym Particles, could himself become well and truly "King of Monsters". But there was a rival.
Devil Dinosaur was the creation of Jack "King" Kirby, who had returned to the Mighty Marvel Bullpen after some years abroad at the Distinguished Competition. He returned with a flourish helming the titles Captain America and Black Panther, as well as creating new ones like The Eternals and Devil Dinosaur. Devil and his caveboy friend Moonboy proved to be a doughty team for nine issues which wrapped a few months before this crossover with Godzilla.
Big G and Devil do what you'd expect, they encounter each other and do ferocious battle, each gathering a smattering of respect for the power of the other.
Later that power is harnessed in tandem to battle the larger threat of the Lizard Warriors who menace the peace of the great valley which Devil and Moonboy protect.
Eventually Godzilla's battles in the deep recesses of the past come to an end as he continues to grow and is drawn back into the modern world of New York City, which must at last finally face the unleashed might of the King of Monsters.
Seeing as how this is the Marvel Universe, the superheroes are assembled to confront the threat of Godzilla and the Avengers take the lead.
Eventually they are able to turn him away from the center of the city if not defeat him, and Godzilla finally at last completes his tour of the great American continent as he steps into the harbor beyond New York City and for the last time in the Marvel Universe disappears beneath the waves of the Atlantic Ocean.
And so it ends, one of Marvel's most unusual partnerships. Bringing Godzilla to the comic book universe had taken much too long and trying to fit the giant monster into the Marvel mythology, even for a relatively short time was a challenge. The massive destruction caused by the monster and the countless people who suffer because of that damage make it incredibly difficult to have any empathy for the fate of the monster who for the most part exists apart from man, who lives by rules which are beyond our control and arguably our understanding. Godzilla is to be endured and like any great storm which finds landfall, the recovering is costly and long lasting.
But that's what makes for a great monster!
For the record Marvel revived Godzilla (sort of) in the pages of Iron Man when it is shown that Dr. Demonicus has gained control of the giant monster and mutated him, altering him sufficiently to stave off lawsuits. They needn't have bothered as the monster they made was too pitiful to sue over.
In the end there's only one "King of the Monsters"!