this could happen easier than a lot of people suspect: Doom has displayed mental powers more than capable of breaking through Hal Jordan's defenses. Superman's weakness and power source are essentially the same thing: types of radiation. Doom has more than a few alternate types of energy projections and draining mechanisms that affect radiation and light spectra. Doom has experience with speedsters in the form of the Avenger's Quicksilver. Between a combination of anti-gravity, inertia dampeners and friction negation Flash is a sitting duck. As for Wonder Woman, he might be able to just out-muscle her but given her mythological origin it wouldn't surprise me if he had mystic means to depower her. Batman's got his work cut out for him; fighting against a man who has stood against Galactus, Strange and Satan, finding the weakness in a suit of armor Tony Stark doesn't begin to understand, controlled by an intellect that rivals multiple worlds' super geniuses.
You do realize the three people Doom fought in what this guy said could beat the main members of JLA? Also, he was able to steal the powers of the Beyonder ( a near omipotent being that can kill Superman easily). Wouldn't be surprised if he created devices to shut each of them down before he went there.
Haha Doom wishes he was that powerful, superman would snap him in half, Wonder Woman would snap him in half Green lantern would beat his ass and the day he catch the flash is the day Hulk stops being angry
Actually, if Dr. Doom knows the weaknesses of Superman and Green Lantern(yellow and kryptonite) he can defeat both of them. With Flash he'll have probably built a device that increases ones personal gravity. Wonder Women is trickier but his suit does make him stronger than the Thing and has a wide variety of weapons built in. Doom's skills as a strategist could allow him to triumph.
Batman however is the best one to defeat Doom because he just as smart, if not smarter, than Doom. And won't bother to fight him head on since he took out Wonder Women and instead have a trick up his sleeve specifically for Doom. It will be a battle of wits.