One idea could be a misunderstanding that leads to a battle. Maybe a villain manipulates the situation so that Young Justice thinks the Justice League has turned evil. For example, the villain uses mind - control technology on some of the League members and Young Justice has to fight to save them.
It's hard to say who would win. The Justice League has more experience and raw power. But Young Justice is more unpredictable and often thinks outside the box. If it was a straight - up fight, the Justice League might have the edge in terms of power levels. However, Young Justice could use their youth and creativity to find weaknesses in the Justice League's more traditional fighting styles.
One idea could be a misunderstanding that leads to a fight. Maybe the Justice League mistakes some of Young Justice's actions as being too reckless and end up in a battle. Then they realize they were wrong when a real threat emerges and they have to work together.
One great 'Young Justice Dimension: Justice League' fanfiction is 'The New Recruits'. It focuses on how new members are integrated into the team. The story has great character development and exciting action scenes.
Miss Martian from Young Justice could be a great focus. Her powers of telepathy and shape - shifting make her a formidable opponent. Also, her experiences as a young hero trying to fit in and be accepted, especially when facing the more established Justice League, can lead to some really interesting character development and plot twists.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3). It has a vast collection of fanfics, and you can simply search for 'Young Justice Justice League deaged' in the search bar. Another option is Fanfiction.net, which also has a large number of fan - created stories. Some Tumblr blogs may also feature or recommend such fanfictions. Just search for relevant tags like #YoungJustice #JusticeLeague #deaged.
In a 'Young Justice vs Injustice League' fanfiction, the Young Justice team might use their teamwork and strategic skills to their advantage. They are younger and more agile, so they could potentially outmaneuver the Injustice League. For example, Robin's detective skills could be used to find weaknesses in the Injustice League's plans.
I'm not sure about specifically 'famous' ones just for this concept. But there are many talented fanfiction writers in the DC universe fanfic community. Some writers might be well - known within the circles of those who are really into Young Justice and Justice League crossovers. They often have a unique take on how the Justice League would interact with and watch over the Young Justice team.
In such a fanfiction, there might be a big threat that requires both teams to combine their skills. The Flash could race with Kid Flash and share some speed - related tips. And Wonder Woman could train the female members of Young Justice in combat.
They might be really surprised. Some fanfictions could show their characters in very different ways than they expect. For example, they might see relationships between characters that they never thought of in the official story. It could be both amusing and a bit strange for them.