With no heroes or law enforcement to stop them, which one of these psychos would rack up the biggest body count in a major city with one day to prepare?
Deadpool while a psycho is more about the payday than anything. He doesn't really go for killing randoms or innocents that much.
Bullseye is a bad guy, but again, he's more about fighting heroes or doing contracts.
Punisher could rack up a huge body count, but he only goes after bad guys, so while the criminal element would take a big dip, he couldn't get super duper numbers.
Now you've got Joker. This guy could probably bomb half the city with a few hours to prepare, and he has no problem killing everyone.
Deadpool.
I can picture Deadpool hallucinating that he is in a video game and running around town shooting, stabbing and blowing people up while laughing and cheering himself on.
Both Deadpool and Frank have gotten their hands on nukes before. Judging from the amount Wade's used last time he fought Hulk he's got loads of it stashed somewhere. So id put him as number 2 with Joker being the obvious winner. Frank is 3rd. Bullseye comes last.
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Azula: My mommy didn't love me so I'm going to burn down your village.
But if this was without stashes etc. I think Frank would be a contender. He would be a beast with a day of prep aimed at the largest possible bodycount, without having to worry about innocents. Bullseye finishes last in every thinkable scenario imo.
Frank for the most efficient followed by Deadpool. Bullseye can suck it and joker for third he isn't efficient at all a bit to preoccupied with this or that to get the job done the best.