With popcorn movies like “Godzilla vs. Kong,” the main thing is getting the tone right. Outside of kaiju cultists, nobody takes this nonsense seriously. So the movie should reflect that.

Comic relief characters like the conspiracy nut Bernie (Brian Tyree Henry), griping about a technocrat as “the woman with the villain hairdo” and the cowardly nerd Josh (Julian Dennison of “Hunt for the Wilderpeople”) are a must.

Ironic vintage pop songs on the soundtrack, underlining the joke? Elvis is a given. “The Air that I Breath” by The Hollies and Johnnie and Joe’s “Over the Mountain, Across the Sea” will do.

“Over the mountain, across the sea
There’s a girl, she’s waiting for me.”

Because on Skull Island, a deaf native girl (Kaylee Hottle) is literally waiting on the big ape to awaken in the opening scene.

As for bad guys, only the best actor never to play a Bond villain (Demián Bichir) fills the bill.

This version of the Battle of the Titans goes deep down a kaiju rabbit hole — center of the “Hollow Earth” deep — as we travel to the place where titanic critters like Kong, Godzilla and their ilk live and carry on until they take the tunnel to the top and make mayhem for us.

There’s this megacorp run by a megalomaniac (Bichir), Apex Corporation, whose giant research facility is mostly underground in the capital of Florabama — Pensacola. That’s where conspiracy nut Bernie has gone undercover to tell the People the Truth.

When Godzilla attacks the place, Bernie looks like a sage, and not just another nut with a podcast. That’s what sends Godzilla Girl Madison (Millie Bobby Brown) and her pal Josh to him. That’s how they infiltrate the facility, without the knowledge of Madison’s “Monarch Corp” scientist and absentee dad (Kyle Chandler). And that’s how they end up in an elevator together.

“How deep does this go?” Josh wonders.

“Hell,” Bernie cracks. “It goes to Hell.”

Rebecca Hall is the scientist trying to keep Kong trapped and placated on Skull Island, but a little late in figuring out the deaf girl can chat with the giant ape via sign language.

Alexander Skarsgård is a barely credible academic, “a sci-fi quack trading in fringe physics,” is enlisted by Big Apex chief to round up Kong to guide them to the center of the Hollow Earth to find something to fend off the Lizard King. He’ll have to win trust of Kong’s keeper and his little gal pal.

The Apex oligarch’s daughter (Eiza González) will tag along and Mean Girl ensure that everybody does what they’re paid to do.

But everybody knows they’re just under-card matches before the Main Event, a slug fest that’ll leave some Pacific Rim megalopolis in ruins with a body count nobody in the movie will be tactless enough to point out.

The fights are epic, and I have to admit, the ever-improving CGI makes Kong the most empathetic he’s been since he was sniffing his fingers around Fay Wray.

I lost interest at the whole magic tech trip to the Hollow Earth — HEAV the “antigravity” powered shuttles are called, for Hollow Earth Aerial Vehicle. Snicker. And really, with NBA players saying out loud that the Earth is flat, do we need to suggest it’s hollow, too?

But there’s a theme park ride joke (and proof of concept) sequence, some splendid brawling in the deep, from ship to ship and all over Hong Kong.

At least one Japanese character is an absolute necessity in this bit of Hollywood cultural appropriation. Remember, Godzilla and Kong tangled before in the cinema of Ancient Japan. And nobody else pronounces Godzilla’s name right — “Gorjirra!”

Kudos to the class of actors who signed on for this, some of them making their second outing in kaiju country. Everybody, especially Henry, Hall and Skarsgård, looks properly over-awed and gobsmacked at their first glance at the impossible, or just very very improbable.

Sure, you’ll feel a little dumber than you were going into all this by the time the credits roll. But that’s always been the point underscoring the more obvious one.

Like the kaiju rock anthem says, “History shows again and again how nature points out the folly of Man.”

MPA Rating: PG-13 for intense sequences of creature violence/destruction and brief language

Cast: Rebecca Hall, Alexander Skarsgård, Bryan Tyree Henry, Millie Bobby Brown, Kaylee Hottle, Shun Oguri, Eiza González, Lance Reddick, Kyle Chandler and Demián Bichir.

Credits: Directed by Adam Wingard, script by Eric Pearson and Max Borenstein. A Warner Bros./HBO Max release.

Running time: 1:53