There are two things that James Gunn does better than just about anyone else on the planet: One is making glossy mega-budget superhero movies that still march to the beat of their own drum (e.g. “Guardians of the Galaxy Vol. 2”), and the other is making over-the-top gore-fests so gross they straddle the line between indie cinema and outsider art (e.g. the darkly satirical “Super,” which in hindsight seems like a mission statement). Gunn might be the only person to direct blockbuster tentpoles for both Marvel and DC, but he’s still the guy who co-wrote Troma’s “Tromeo and Juliet” at heart. And by the time the opening credits of “The Suicide Squad” are spelled out in the head blood that seeps from a supporting character’s freshly exploded skull, it’s clear that he always will be.

The most fun and least depressing superhero movie in a very long time, Gunn’s deliriously ultra-violent “The Suicide Squad” wears the yoke of its genre with a lightness that allows it to slip loose of the usual restraints, if not quite shake them off altogether. It must be liberating to make a $150 million (give or take) mulligan for a widely maligned disaster that still managed to gross almost a billion dollars despite becoming a punchline along the way, and that’s really what this unhinged carnival of R-rated cartoon mayhem amounts to at the end of the day: Not a reboot of or a sequel to 2016’s “Suicide Squad,” but rather a second draft.

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In the brief yet purgatorial history of superhero movies — which once gave us three different Spider-Men in the span of nine years — we’ve never really gotten the chance to watch such wildly divergent takes on the same characters, played by several of the same actors, in the same cinematic universe. And while the tone of Gunn’s film isn’t far removed from that of its misbegotten predecessor, this one actually has the chutzpah (and the creative freedom) to make good on Harley Quinn’s whole “we’re bad guys — it’s what we do” routine. Sometimes the difference between a strike-out and a home run is just a slightly harder swing at the ball and some help from a giant alien starfish who grows bigger each time one of the vile flying pods it excretes from its body face-hugs a new victim and indoctrinates them into the hivemind (or hive… central nervous system). But we’ll get there.First we have a premise to set up and a team to build, and Gunn’s script leverages — and subverts — genre expectations on both fronts. Most of these movies tend to start with a mess of unrelated mishegoss before the main story kicks into gear, but “The Suicide Squad” ambles out of the gate with the confidence of a movie that’s totally comfortable in its own skin (even if that skin is a technicolor patchwork of glowing polka-dot-like tumors). Once again the action begins inside Belle Reve prison, where ruthless fed Amanda Waller (Viola Davis) uses the local population as her personal draft pool from which to recruit black ops teams of supervillains in order to do the dirty work that America’s government would rather deny. “I’d do anything to get out of this hellhole,” carps one of the inmates. “Welcome to anything,” Waller replies.

And that’s it. What more do you need? The next thing you know, a long row of weirdo killers are walking toward a military plane in slow-motion and waiting to be dropped onto the beach of a fictional Central American country named Corto Maltese (an evocatively performed role that’s split between Panama and Pinewood Studios). Why are they going there? They don’t know, and some of them won’t survive long enough to find out; the bench of C-grade comic book characters that Gunn has assembled here is so deep that his movie can explode half of them into small pieces without missing a beat.

Needless to say of a team that includes a humanoid weasel (Sean Gunn) and Pete Davidson, the goofy rogue’s gallery of “The Suicide Squad” cleaves much closer to the Mystery Men than it does to the posturing group of amoral badasses who featured in the previous film; if you’ve ever wanted to see the DCEU adopt some of the sarcastic, wide-eyed, “am I really fighting alongside a homicidal raccoon?” energy of “Guardians of the Galaxy,” this is definitely your lucky day. But here Gunn is able to push the envelope much further than he ever was on the other side of the fence, and while some of his characters are more compelling than others, all of them are dressed with a degree of moral compromise that the Avengers and their friends have only worn as cosplay.

That starts with John Cena’s Peacemaker, an almost parodically swole mega-patriot who acts like a lovable cross between Captain America and Madison Cawthorn, and says things like “I cherish peace with all my heart — I don’t care how many men, women, and children I need to kill to get it” (Gunn’s digs at the United States’ foreign policy aren’t exactly subtle, but at least he never backs down from them). Cena’s strongman comic schtick is so much funnier when it belies a certain weakness, and “The Suicide Squad” uses him more effectively than any movie since “Blockers.” Although you’d have to go all the way back to the end of 1988’s “Akira” to find a precedent for the “cool but imminently catastrophic” level of vein-bulging that’s happening in Cena’s biceps here.