Gamora and Sakura could be a great pairing. Both are strong female characters. Gamora could teach Sakura some of her advanced combat techniques from other planets, and Sakura could show Gamora how to use medical ninjutsu. They could also bond over their experiences of growing up in tough environments and having to prove themselves.
Definitely Thor and Star - Lord. Thor is this god - like being from Asgard, and Star - Lord is a half - human, half - alien space adventurer. Their personalities are quite different. Thor is more noble and straightforward, while Star - Lord is a bit of a scoundrel. But they both have a sense of humor and a love for adventure. They could have some great banter while fighting side by side.
I think Groot would be really interesting. He has a simple yet profound nature. In a Star Wars - Guardians crossover, his unique form of communication and his strength could be used in very creative ways. For example, he could befriend some of the more nature - oriented species in the Star Wars universe like the Ewoks.
I think the meeting between Thor and Groot would be fascinating. Thor, being an Asgardian god, and Groot, a sentient tree - like creature. Thor might be initially confused by Groot's limited vocabulary ('I am Groot'), but as he gets to know him, he would see Groot's strength and loyalty. Groot could also be intrigued by Thor's lightning powers. And their combined strength in a fight against a common enemy would be a sight to behold.
Luna and Bunny would be a cool pair. Luna is all about music and has a wild side, and Bunny is very no - nonsense and responsible. They could learn a lot from each other. Luna could teach Bunny to loosen up a bit with some rock music, and Bunny could teach Luna about discipline and focus in their fight against the common enemy.
Naruto and Star - Lord would be likely to interact. Naruto's friendly and outgoing nature would draw him to Star - Lord's charisma. They both have a sense of adventure and a desire to protect their own groups. Naruto might be curious about Star - Lord's blasters and spaceship, while Star - Lord could be interested in Naruto's ninjutsu.
Black Widow and Nebula would make for an interesting pair too. Both are strong female characters who have had a rough past. They could bond over their experiences of being in the shadow of more powerful male figures in their respective groups. And they could also team up to take on some of the more dangerous enemies, using their stealth and combat skills.
Another great pairing could be Hulk and Groot. Groot's calm and gentle nature might have an interesting effect on the Hulk. Maybe Groot could help calm the Hulk down when he's about to go on a rampage, or they could team up in a fight and Hulk could use Groot as a sort of living weapon. It would be a very unique dynamic.
I think Star - Lord and Iron Man would be an interesting pair. They both have a cocky and self - assured attitude. They could compete in terms of who has the cooler gadgets and who is better at coming up with quick - witted plans during battles. They might also argue about music, as Star - Lord is always into his retro tunes while Iron Man probably has his own favorite modern music.
It's hard to say for sure, but Doctor Strange could be a very powerful character if he were included. His mastery of the mystic arts could give him an edge in both the magical and space - faring aspects of the story. He could manipulate time and space in ways that would be useful in the Guardians' adventures and also hold his own against powerful wizards in the Harry Potter world.
Naruto and Oga Tatsumi would be really interesting. Naruto's positive and determined attitude would contrast with Oga's rough and delinquent - like personality. They could learn a lot from each other, like Naruto teaching Oga about the importance of friendship in a more idealistic way, and Oga showing Naruto how to be tougher in a more down - to - earth way.