The interaction between Starfire and Beast Boy would be fascinating. Beast Boy can transform into different animals, and Starfire has her own set of superpowers. They could have some really fun and comical moments together, like when Beast Boy turns into a small animal and Starfire is trying to figure out how to communicate with him. Also, they could team up in battles in really creative ways, with Beast Boy using his animal forms to distract enemies while Starfire blasts them with her energy.
I think the interaction between Red Robin and Batman would be the most interesting. Since Red Robin is Batman's protege, seeing how their relationship plays out in the context of the Justice League would be cool. Maybe Batman would be more protective or more critical of Red Robin in front of the other League members.
Robin from Young Justice and Agent A would likely have an interesting interaction. Robin is highly intelligent and a great detective in his own right. Meeting Agent A, who may have different methods of investigation, could lead to some really cool exchanges. They could compare notes on cases and share their insights on solving mysteries.
Definitely Damian and Superboy. Superboy has his own issues with identity and control, and Damian's strong sense of self and discipline could either clash or create an interesting dynamic where they learn from each other. Maybe Superboy could teach Damian about the importance of emotions, while Damian could show Superboy some combat techniques.
Definitely the interaction between Nightwing and Robin (from Young Justice). Since Nightwing was once Robin himself, he could offer a lot of wisdom and guidance to the younger Robin. Also, the interaction between Nightwing and Artemis would be great. They both have a lot of combat skills and a bit of a sarcastic side, so their banter would be really fun to read. Another interesting one would be Nightwing and Superboy. Superboy might look up to Nightwing as a more experienced hero and Nightwing could help Superboy better understand his powers and his place in the hero world.
I think Batman and Robin (from Young Justice) would be really interesting. Batman's brooding and strategic mind against Robin's youthful enthusiasm.
I think Billy Batson and Robin would make an interesting pair. Robin is all about strategy and detective work, while Billy has that child - like wonder and raw power as Shazam. They could learn from each other. Robin could teach Billy how to better analyze a situation before jumping into action, and Billy could show Robin that sometimes it's okay to rely on pure power and instinct.
The interaction between Spider Man and Superboy could be fascinating. Superboy has his super - strength and invulnerability, which is very different from Spider Man's more agile and acrobatic powers. They could have a friendly rivalry, like who can take down more bad guys in a fight. And Superboy might be intrigued by Spider Man's human side, as he often struggles with his own identity as a clone.
It could be Robin. Since he has a connection to Batman like Red Hood, he might have a unique perspective. He could be the one trying to understand Red Hood's motives and trying to bridge the gap between Red Hood and the rest of Young Justice. Also, his own growth as a hero could be further developed through this encounter.
One interesting storyline could be Starfire's unique powers interacting with the Young Justice team's abilities. For example, her starbolts might combine with Superboy's strength in a new way during a battle. Another could be her learning about Earth's culture from the Young Justice members, leading to some comical misunderstandings.
The interaction between Robin and Batman would be really interesting. Robin has his own identity with the Teen Titans now, and Batman is his former mentor. There would be a lot of unspoken history and emotions. Batman might be proud of how Robin has grown, but also a bit overprotective. And Robin would be eager to show Batman that he can handle himself without his constant guidance.