First, GL can improve his visual acuity with his ring- he's created binoculars and telescopes before. Second, remember, the main limitations on an Oan Lantern's power are 1) the color yellow, 2) their willpower. He could make a personal GL Hubble in orbit for targeting purposes.
The issue there is that the wearers of the GL ring don't generally have the cognitive ability to do orbital mechanics in their heads. Superman does.
Add to that, the power rings allow GLs to manipulate matter at an atomic level and screw around with electomagnetic energies on (almost) all wavelengths. How do you think most Avngers would handle a burst of hard radiation. (OK, the Hulk would be happy to tan in some more gamma bursts...) Theoretically, GL could do an EMP. How Iron Man and the Vision would like that would depend on how strong it was.
It has been noted that they are limited by their own knowledge, cognitive abilities, and understanding, however - in order to make a construct put out kryptonite radiation, Hal needed coaching from Batman. Hal is not a world-class *scientist*. Guy Gardner was even less bright. He got beat up by a cat. Not a super-powered, Kryptonian cat. Just a plain-old, ornery yellow cat. One Green Lantern (Ch'p) died
getting run over by a truck. Just a yellow truck. Not even in a fight. Which is to say, being a GL does not make one a genius. They are impressive, but not all-powerful unless the writers are forgetting themselves.
The real point I was making, however, is that while Supes is in play without restriction, the rest are superfluous. If we don't have the Avengers beating Superman, the rest of the debate is completely irrelevant. And the Avengers probably can't do that without knowing Superman's weaknesses.
Along with Superman & The Flash, he is one of the few characters who can travel in time unaided. Great for intelligence work...or for giving someone the Weeping Angel treatment. Time traveling Avengers stories almost always involved Kang's platform or some other device.
Well, now you are probably stepping out of the movie universe, and into the comics universe. At that point, I thin you'll find that probably every major DC character has done time travel on their own at some point or other. But the *movie* GL has not shown this ability, has he? Not to mention, none of these time-travellers should be doing so unless it is *absolutely necessary*. Superman and the Flash don't travel in time *every instance* in which they might get beat up. It is not their Big Red Win Button.
And there is no reason he couldn't use a combination of a force bubble prison followed by a fling into the void of space- all at extreme range- to take care of most targets.
As I said - if the Hulk throws a school bus at him, he is still squished.
(Actually, that's only traditionally - in the comics these days, the yellow-weakness has been removed.)