system
Given the following post, respond as if you're commenting on Reddit:
human
(DC) Why did the guardians of the galaxy (green lantern) request help from the Justice League?

Green Lantern is in the Justice League, and the guardians monitor the lanterns. They must know about them but even in Crisis On Infinite Earths they just say "We need the complete Green Lantern corps. And even then I fear for our success."

And surely there must be another group(s) of superfriends like the JL in the universe somewhere. Why not just tell all the lanterns to get their groups of superfriends for an enemy threatening the universe?

Edit: I meant Guardians of the Universe. I'm a dumbass.
gpt
There are other planetary teams, yes, but their powers are either highly situational, to the point where it only really works on their planet, or they're incompetent.

That said, the Guardians are also a little arrogant and believe that the Green Lantern Ring is the ultimate weapon in the universe. Which it is. A skilled ring slinger could thrash the entire League if they tried. Even Hal Jordan had plans for such back in the 70s or 80s.

Even without that, the Green Lantern Corps consists of 3600 people. 7200 in modern times. The addition of six or seven more individuals, of varying power levels, honestly wouldn't affect things that much.