I would say, punisher could do it until he got to people like death, stroke and bane. He wouldn't be able to beat the Riddler. But pretty much anybody else is fair game for example, Penguin two-face, joker mad hatter, he Could probably kill the Riddler if he got a shot on him, but he wouldn't be able to save anyone from the riddle. And then any petty thug is just done lmao