One possible plot could be that the Voltron team gets transported to the Avengers' universe. They might initially be seen as threats, but then they realize they need to team up to fight a common enemy, like a powerful alien force that's too much for either group alone. The Voltron lions could combine in the middle of New York City, creating an amazing spectacle.
A really interesting plot could be a time - traveling crossover. Supergirl goes back in time to the era of the original Avengers. She helps them in a battle that changes the course of history. In return, the Avengers help her find a way back to her own universe. During this time, she forms a special bond with Thor, as they both have superhuman strength and a connection to otherworldly powers.
One possible plot could be that the Master Chief is somehow transported to the Avengers' universe. He teams up with Iron Man to stop a new threat that combines Covenant and Hydra technology. Their combined skills in combat and technology would make for an exciting adventure.
One possible plot could be that Superman is somehow transported to the Marvel universe where the Avengers operate. He initially clashes with them due to misunderstandings. For example, his super strength might be seen as a threat. But then they realize they can team up to fight a common enemy, like a powerful alien or a super - villain who has the ability to manipulate time. They combine Superman's powers such as heat vision and flight with the Avengers' diverse skills like Iron Man's technology and Captain America's leadership to save both universes.
It could involve different timelines of the Avengers coming together. Maybe the Avengers from the original team meet their counterparts from an alternate universe where things like Tony Stark never became Iron Man in a different way. They have to team up to fight a common enemy that threatens all the universes.
The plot might involve a villain who has the ability to control both technology and Pokemon. The Avengers are called in because their experience with high - tech threats is needed. They meet up with Pokemon like Charizard, who can fly them around and provide firepower. Meanwhile, Pokemon trainers teach the Avengers about the different types of Pokemon and how to use their strengths. For instance, Black Widow could be paired with an Eevee that evolves into Sylveon and uses its fairy - type moves to help in battles. Together, they work to stop the villain from taking over both the Pokemon world and potentially other dimensions.
One possible plot could be that Superman is somehow transported to the Marvel universe. He might initially be seen as a threat by the Avengers. But then they realize he's there to help against a common enemy, like a powerful cosmic villain. They would team up, with Superman's super strength and flight abilities complementing the Avengers' various skills.
A plot could involve the Avengers trying to understand the concept of alchemy. Maybe Tony Stark becomes really interested in it and tries to incorporate it into his tech. Meanwhile, the Fullmetal Alchemist characters are in awe of the high - tech world of the Avengers. They could end up sharing knowledge and skills to take on a powerful foe that neither could defeat alone. For example, a powerful demon from the Fullmetal Alchemist world that has found a way to use advanced weaponry from the Avengers' world.
A cool plot might be that the Tailed Beasts in the Naruto world are being targeted by an unknown force from the Marvel universe. The Avengers, thinking it could lead to a greater threat to both universes, come to help. Naruto and the Avengers have to work together to protect the Tailed Beasts. Hulk could have an interesting interaction with the Tailed Beasts, perhaps learning from them how to better control his rage, while the ninjas are amazed by Thor's lightning powers and try to incorporate some of that into their own jutsu.
A plot could involve BTS being transported to the Marvel universe. They initially struggle to understand the new world and its rules. But they soon realize that they have unique abilities that can be of great help. Maybe the Avengers are facing a new type of enemy that the BTS boys' music can affect in some way. For instance, their positive and energetic music could weaken the villains who thrive on negative energy. The BTS members then team up with the Avengers, each member pairing up with an Avenger to learn from them and also share their own skills. For example, Jimin could pair with Black Widow and learn combat skills while teaching her some of his dance moves that can be used in a fight for distraction.
Perhaps the Joker discovers a way to mind - control some of the Avengers. He targets Hulk first, making him go on a rampage in a major city. The other Avengers are caught off - guard. They soon realize it's the Joker's doing. Spider - Man, who has recently joined the Avengers, swings in to help. He uses his agility to dodge the Hulk's attacks and tries to figure out a way to break the mind - control. Doctor Strange is called in to use his magic to counter the Joker's mind - games, and the team must fight both the controlled Avengers and the Joker's minions to save the day.