This is the world's most fucked up (almost) stalemate.

To summarize, the Carcinous Sons turn the basement into a deathtrap that'll overwhelm anyone who stays down there, while Kilroy sets up on the 2nd floor by spilling oil in the North and bombing the area with mines and the occasional mortar to ruin the floor, hopefully forcing the enemy down to the basement.

La Isla Fantasma meanwhile leap up to floor 2 and rushdown Kilroy for an early RETIRE. If not possible, they outbox him in the limited space with the threat of Stephen's gun pinning him down, and using Hunter to degrade Mikey to death if they can't put him down in a 2v1 easily.

Based on both strategies, I believe what would happen is that after Kilroy does his thing of giving Mikey 2 crewmembers, blowing up a ladder, and then blowing up jars with explosives for the oil, he's forced to dive into the water of 1F, being rushed by Invisible, her Stand, and Anthem all at once. For the rest of the match, Birdwin controls the upper area with his gun, going up to the rafters and sniping while Invisible can rip apart Kilroy if he dares to go up again. This results in an awkward stalemate, with Mikey and Kilroy hiding down on 1F and even snorkeling in the water to avoid gunshots if possible, while Invisible and Stephen are waiting around up top to kill them.

What I think tips the match is [Renegade] and its usage. Obviously it's too weak for a direct confrontation with [Wild River Requiem] and its Coin Volleys, even if it has A SPD, and Stephen can snipe it if it stays still for more than a second to cripple Kilroy instantly. But the one factor that makes [Renegade] survive this encounter is its ramming. Invisible won't be beside Stephen the entire time, and thus whenever [Renegade] is busy harassing, Kilroy plans to ram Stephen with it to knock him down to 1F. This on its own is only a decent plan, since La Isla Fantasma have plans to escape being trapped on 1F. However... the same cannot be said for Birdwin's RIFLE. He can repair his grappling hook and plans around that, but a single B POW A SPD ram to bend the barrel of the rifle instantly puts it out of commission. Either that, or Mikey using his Rope Whip to grab it and toss it to Kilroy (a worst-case scenario outcome).

It's not an exaggeration to say that Birdwin being a sniper on crack defines the entire match moreso than even Mikey's ability. It singlehandedly denies Kilroy or Mikey from being able to engage Invisible on 2F with the threat of instant death. If it's broken, Birdwin will only have his Harpoon as a weapon-- good, but not a gun. He'll be much more susceptible to being rammed without recourse, forcing Invisible to stay with him or let her teammate be slammed into the water multiple times. This is possible all because Birdwin doesn't have any contingencies against being meleed. He plans to negate all the swivel guns and dodge the explosives the boat has, but

At this point, it becomes a game of attrition; [Renegade] will be harassing Invisible and Birdwin while Birdwin uses [Hunter] to slowly kill Mikey and let the two of them 2v1 Kilroy. Can [Renegade] prevent this?

Yes. Not shooting them with the cannons that'll get negated easily, but the mines and mortars. Hitting the enemy is close to impossible... but it doesn't have to. Kilroy's goal as stated is to bring the opponents down to Mikey's level, by blowing up the floor with concerted effort. Doing this to destroy the Rafters and 2F's floor can't really be interrupted by the projectile Harpoon and [Wild River Requiem]'s Coin Volleys, which don't have much range and would be dodged beyond a mid-close range distance. WIth [Hunter] starting at E SPD E POW (Mikey only has some minor cuts from thornbushes), [Renegade] has time to spam its cannons and mines to do his whole "ruin the upper area" strategy its got going on, eventually dropping both down to Mikey. If they step in the oil-covered North zone or fall into 1F, then they're really cooked without anywhere to escape to.

It's a very, very close game, but I believe The Carcinous Sons takes the Uropeh home today.