A plot could involve Batgirl investigating a mystery that leads her to a Young Justice member who seems to be involved in something suspicious. As she digs deeper, she discovers that the member is actually being framed. Together, they work to clear the member's name and expose the real villain behind the frame - up. During this process, Batgirl becomes an honorary member of Young Justice for a short time and participates in some of their team - building activities.
Maybe Batgirl is sent by Batman to assist Young Justice on a mission. She has to adapt to their more light - hearted and less brooding approach compared to the Bat - family. Along the way, she forms a special bond with a particular member of Young Justice, perhaps Artemis. They have to overcome their differences, like Batgirl's strict no - killing rule and Young Justice's sometimes more lenient attitude towards villains, in order to succeed.
The plot might center around a mystery that ties to both Young Justice's world and Batgirl's. For instance, some sort of ancient artifact that has the power to disrupt both the meta - human world and Gotham's criminal underworld. Young Justice brings their diverse powers and abilities, while Batgirl offers her detective skills and knowledge of Gotham. As they search for the artifact, they face various challenges and enemies.
One plot idea could be that Supergirl, while on a mission in a new city, accidentally crosses paths with the Young Justice team. They initially mistake her for an enemy due to her Kryptonian powers being so strong. But as they get to know her, they realize she can be a great ally. Another idea is that there's a powerful villain who is specifically targeting Kryptonians and the Young Justice team has to work with Supergirl to stop this threat. They might learn new fighting techniques from each other during the process.
Another plot could involve Damian being sent on a mission by Batman to infiltrate Young Justice, thinking there might be a mole or some sort of internal problem. But as he spends time with the team, he starts to actually care about them and has to decide whether to complete his original mission or protect his new friends.
Maybe a plot where there's a competition between the two groups. A powerful and eccentric billionaire sets up a series of challenges across the city. The winner gets a large sum of money for their cause. At first, it's all about competition, but as the challenges get tougher and more dangerous, they start to cooperate and combine their resources to complete the tasks. This also leads to some friendly rivalries and new friendships forming.
Another plot could involve Raven being sent to the Young Justice world by some dark force. She has to adapt to this new place and team up with them to find a way back home while also dealing with the local villains. During this time, she could form unique bonds with the different members of the team. For instance, she might find a kindred spirit in Superboy due to their both being sort of outsiders in their own ways.
One idea could be that Nightwing has to train the Young Justice team in some new combat techniques. Maybe there's a new threat in Gotham that requires their combined skills to take on. Another could be a time - travel plot where the Young Justice team gets sent back in time and meets a younger Nightwing, and they have to work together to get back to their own time. Or perhaps Nightwing goes undercover in Young Justice to investigate a mole, leading to a lot of mystery and drama within the team.
One idea could be that the Bat family is investigating a strange series of crimes in Gotham. Meanwhile, the Young Justice team stumbles upon a lead that takes them to Gotham as well. They initially clash due to different methods of operation. Batman tries to keep his family in line while also dealing with the young, headstrong heroes of Young Justice.
One idea could be a crossover where the Young Justice team has to team up with the Justice League to face an interdimensional threat. Maybe a powerful villain from another dimension is trying to invade Earth and the combined skills and powers of both groups are needed to stop it.
Maybe a story where some of the younger members of the Young Justice team are frustrated with the Justice League's methods and decide to take on a mission on their own, but end up getting in over their heads and have to call in the League for help. This could lead to a lot of character development and some interesting dynamics between the two groups.
One interesting plotline could be them having to deal with a new and powerful villain that specifically targets their relationship. For example, a villain who tries to turn them against each other by manipulating their past traumas. Another plotline might be them training a new group of young heroes in Young Justice together. It would show their different teaching styles and how they complement each other.