Alright so I've been called here yet again, so welp here am I, now for this one's analysis I'm going to to follow the "who would win" type analysis like the Tank vs Anime post that came after this one instead of the "how one could win" type analysis, as it is what's specifically requested here, and so here we go.
So, on the Boys side we have soldiers in standard combat outfits, Kevlar armor, helmet, gears, etc, and also one guy using the T-45 power armor from Fallout 76, as for their armament let's say they used the AAA's current set of weapons, M16s, Ak-47s, you name it, for the Anime side they have USS Iowa, Megumin, The Dragon, Nezuko, and a random wolf girl, the Iowa got 406mm, 127mm, 40mm, and 20mm cannons, Megumin has explosion, Dragon had regular dragon powers, Nezuko has demon powers, and wolf girl... well she's a human but with wolf senses, that's all, so to level the playing field I'd gave her some weapons, the G36 should be alright.
And now, which side side is going to win?, well fortunately (or unfortunately, depends on how you look at it), it depends, specifically it depends on the loadouts carried by the Boys side, here's why :
So basically the Anime characters vulnerability to bullets are different with each one, some more than others, with the toughest being Nezuko, she has rapid regeneration powers that can grow even missing limbs, so the way to deal with her is with some form of explosive, so that the damage she would sustain would overwhelm her own regeneration, RPG-7 with TBG-7V, which is an anti personnel warhead, is one of the weapons that can be used to deal with her, grenades and grenade launchers may be useful, but it lacks the sufficient damage that the TBG-7V has, and so this is why the loadouts mattered a lot, if the Boys we're only carrying battle rifles and grenades, maybe sniper rifles, it would be a tough fight, particularly when facing Nezuko and Iowa, so in that case both sides had a roughly equal chance of winning, but Anime side's chance is just a tiny bit higher, however if they're carrying more heavier weapons, like rocket launchers and anti personnel mines, they'd have a higher chance of prevailing, this battle also depends heavily on what kind of place they're fighting in, the state of the weather, and most importantly, the combat training of the two sides, training is of the utmost importance when it comes to who's side going to win.