In fight classifications, “Fighting with My Family” is a featherweight  — a no-strain showing comedy that’s easy to pin, even easier to like.

It’s fun.

British funnyman Stephen Merchant steps out of his pal Ricky Gervais’s shadow, writing and directing this WWE-approved “true story” of a British wrestling family with goals of Wrestlemania glory.

Merchant, who also has an amusing bit part in the picture, maintains its inherent Englishness while appeasing the talent behind it — Dwayne “The Rock” Johnson — tailoring it for American audiences and American versions of the British as punchline.

So a needy, skinny wrestler earns an “Oliver Twist” zinger — “Please sir, can I have some more?” The pale, teen heroine of the piece earns “dropout from Hogwarts” lines, Ozzy Osborne references and that old American stand-by put-down, her “English dentistry.”

Yes, the jokes are mostly low-hanging fruit, and quite a few of them you’ve seen and heard in the trailers. But they’re still funny. And Merchant didn’t let the trailers give away the whole movie. Not by a long shot.

“Fighting” is about the Knights, a group of grapplers from “Norwich,  the mustard capital of England!”the mustard capital of England!”

Ricky (Nick Frost) and Julia (Lena Headey, never funnier) have raised their kids in the family business, their low-rent World Association of Wrestling.

Even as tweens, if Zak had a beef with Saraya, settling it had wrasslin’ rules.

“He’s CHOKING me!” might earn a scolding from dad, “THIS is how you choke her out,” and a stern “What are you gonna DO about it?” for “princess” Saraya. She was a quick learner. She had to be.

In the mid-2000s, they drag a ring, ropes and a few wrestling colleagues into tiny English venues that hire them for a pittance to put on a show. Zak Zodiac (Jack Lowden) and Brittani, as Saraya (Florence Pugh) bills herself, are the stars of this “family feud.”

They may take garbage can lids to the face and hard tumbles against the turnbuckles, but their dream is stardom with America’s WWE.

Shockingly enough, they get their shot when a coach and scout for the entertainment company shows up told auditions during a WWE event in London.

Hutch (Vince Vaughn, terrific) knows every Harry Potter putdown even as he dangles the big dream in front of his prospects. He’s looking for “that spark,” and that cockiness that WWE wrestlers and their trash-talking TV patter are famous for.

And he wants to know “if you see yourself as a six inch action figure,” one of the perks of fame.

Zak, who has dreamed such dreams since he was three, doesn’t have whatever “it” is. But Saraya, the pierced Goth girl daughter of a burly ex-con (robbery) and a high-mileage recovered junky, does.

“Fighting With My Family” follows her pursuit of the family dream and her questioning of whether it is truly HER dream as she is sorely tested at WWE boot camp in sunny, scenic Orlando.

“Before you leave Orlando, at least one of you will be a stripper,” Hutch cracks, as he puts beefcake men and towering, busty ex-cheerleader “divas” — and Saraya — through his training wringer.

Merchant, who plays the father of Zak’s fiance, introduces all manner of wrestling and personality stereotypes into the script, and then punctures them. He rubs the edge off almost every one — mean girls, callous coach covering his own personal pain, the works.

And he works the film’s producer and bankable star, Johnson, into some cute, funny and pivotal scenes that are all part of the image burnishing that’s a subtext of this WWE production. Johnson knows his way around a one-liner and lends his sparkle to the proceedings.

We pick up on “the script” for matches, the “soap opera in spandex” that plays out, negotiations that go on between promoters and wrestling providers (“How much for a bowling ball to the balls?”) and gain an appreciation for the danger and precision choreography involved. And we are encouraged to buy into the notion that winners and losers aren’t pre-ordained.

“Fighting” also offers just a hint of the blood and staged mayhem of the bottom rung of the wrestling ladder, which Mickey Rourke’s “The Wrestler” dwelt in.

Pugh, of TV’s “The Little Drummer Girl,” has both star quality and an underdog’s build that makes her portrayal work. She’s shorter and thicker than the ex-models she’s competing against to become a “Diva,” and she manages the film’s emotional tugs with ease.

Lowden, of “Dunkirk” and “Mary Queen of Scots,” does a fine job of conveying bitter disappointment that Zak wants, more than anything, to hide.

Vaughn has grown more subtle with age, and nobody is better than Johnson at playing The Rock.

But Merchant’s canny casting of Frost, Simon Pegg’s better half in movies like “Hot Fuzz” and Headey, best known as the fiery/sexy queen of Sparta in “300,” is what really makes this formulaic “fight picture” sing.

Frost makes Headey funnier, simply by proximity. And she makes him sensitive just in the way she plays off him, a needy, frank ex-addict and who reveals mothering instincts and ring ambition that you’d figure never took hold in Julia.

Whatever happens with Saraya, it takes her many encounters with her folks to make her realize the stakes, to give substance to “the dream” and make all those “frog splashes,” “diving DDTs” and “reverse Frankensteiners” worth it.

And that makes this fighting “Family” a contender.

MPAA Rating: PG-13 for crude and sexual material, language throughout, some violence and drug content

Cast: Florence Pugh, Dwayne Johnson, Nick Frost, Lena Headey, Jack Lowden and Vince Vaughn

Credits: Written and directed by Stephen Merchant. An MGM/UA release.

Running time: 1:48