15Take the Fight to Space
The home team always has the advantage. Being from Earth, the Avengers have a fairly small stadium to play in. The Guardians have all of known space to call home. Sure, Thor is technically an “alien”, but spend enough time with Natalie Portman and you kind of revoke that card,
not to mention the fact that he has lived what seems like a pretty sheltered life on Asgard (seriously, how does he not know who that purple guy who hates standing is?). As for his teammates, the craziest thing they have ever seen is an alien spaceship slug flying up Lexington Ave. and Erik Selvig in his underwear, which is just a normal day in the life of the GotG. So if they want to stand a chance against Earth's Mightiest Heroes, it would definitely help to take the game to outer space.
While the vast of majority of the Avengers are trying to wrap their minds around why there's a talking duck sipping martinis walking by, the Guardians of the Galaxy can swoop in for the win. Simply put, the Avengers are not ready to handle what the rest of the cosmos have to throw at them. This might change after Infinity War, but as of today, how many Celestials have they killed? Oh yeah, and what happened when Tony Stark flew off into space to pull an Independence Day on the Chitauri mothership? Severe PTSD. What happened when Peter Quill nearly froze to death after jumping into space to save Gamorra? An impromptu dance off. Obviously, the two sides have vastly different ways of handling what the cold abyss will throw at you. That's something the Guardians can definitely use to their advantage.