While DC's Iron Man actually made the weakness to color not as ridiculous. During a battle with Marvel's version of Green Lantern known as Doctor Spectrum, the Armored Avenger unleashed a color-based attack that was far more logical in comparison.
Remarkably, Green Lantern's power ring used to simply shut down in the face of the color yellow, being ineffective against everything from lemons, rubber ducks, to anything simply painted yellow. Eventually, this bizarre weakness was retconned by DC writer Geoff Johns who revealed that the fear entity Parallax was responsible for the "yellow impurity" found within Green Lantern rings. Parallax had apparently been imprisoned by the Guardians of Oa within the Green Lanterns' Central Power Battery, resulting in the yellow color of fear becoming a weakness with Lanterns constantly needing to charge their rings from the Power Battery. Once Parallax was released, the yellow impurity became something the individual Green Lanterns could overcome.
However, the retcon explanation doesn't change the fact that the weakness to color was infamously dumb and very strange, one that Marvel Comics improved upon when Iron Man fought Doctor Spectrum in 1963's Avengers #70 from Roy Thomas and Sal Buscema. Wielding his prism of power, Doctor Spectrum is very clearly Marvel's version of Green Lantern, often fighting alongside Hyperion (Superman), Nighthawk (Batman), and The Blur (Flash). However, when Doctor Spectrum and Tony Stark went one-on-one, Iron Man fired a blast of ultraviolet light, weakening Spectrum as it was explained that UV light was outside of the spectrum of color he controls, providing logical reasoning behind the weakness itself.
Rather than simply being weak to a primary color with no explanation for years, Spectrum being susceptible to a color his powers don't extend to makes a lot more sense. There was logic and reasoning for the aversion to UV light, and as such it makes the battle between Iron Man and Spectrum more believable and entertaining as a result. Ironically, the flaws and weaknesses of Marvel's facsimile of Green Lantern made more sense than those of the original Lantern himself.
Regardless, DC Comics would ultimately do away with the "yellow impurity" for the most part, relegating it to a weakness experienced by new recruits to the Green Lantern Corps as an obstacle to be overcome using willpower. As such, the retcon provided new avenues and stories to be told such as Sinestro's formation of his own corps wielding the yellow light of fear. Had the impurity still been an insurmountable weakness in the Green Lanterns' power rings, the Sinestro Corps would have destroyed them in seconds. In any case, it's pretty funny that Iron Man's battle with Marvel's Green Lantern cracked the code on how to make a color weakness not quite so ridiculous years beforehand.
