Another plot could involve Deadpool being hired by some shadowy figure in the RWBY world to take out a particular target. But as he gets to know the target and the RWBY gang, he starts to have second thoughts. His moral compass, which is already a bit wonky, gets even more twisted as he has to decide between his job and doing what he thinks is right in this new universe.
One idea could be Deadpool getting dropped into the RWBY universe and thinking it's some sort of crazy new mission. He starts trying to team up with the RWBY girls, but his chaotic nature constantly causes misunderstandings. For example, he might mistake a Grimm for one of his usual foes and go after it in his own wacky way, much to the confusion of the RWBY characters.
One idea could be that they team up to take on a new super - villain who has the ability to manipulate time. Deadpool's unpredictability and Spiderman's quick thinking would make for an exciting combination in this scenario.
One idea could be Deadpool trying to join the Avengers in his own wacky way. He might show up unannounced at the Avengers Tower, causing chaos and confusion among the team members. Another plot could involve Deadpool being hired by a villain to disrupt the Avengers, but then he has a change of heart halfway through. Or perhaps Deadpool accidentally travels to an alternate universe where the Avengers are very different, and he has to find a way to get back while also dealing with this strange new team.
One idea could be that they are both transported to an alternate dimension. In this dimension, all the rules are different. Deadpool's healing factor doesn't work as well, and Harley Quinn's usual weapons are useless. They have to rely on each other's skills and knowledge to find a way back home. Along the way, they meet strange versions of their friends and enemies, which adds to the hilarity and confusion.
One idea could be that Deadpool and Spider - Man team up to take on a new supervillain who has the ability to manipulate time. Spider - Man uses his quick thinking and acrobatic skills, while Deadpool's unorthodox fighting style and regeneration ability keep them in the fight.
One idea could be the characters from RWBY ending up in the world of Overlord. They might initially be confused and have to adapt to the new, more dangerous environment. Maybe Ruby could mistake some of the Overlord's minions for Grimm and attack, causing a stir among the various factions in the Overlord world.
One idea could be that the characters from RWBY are transported into the Destiny universe and have to learn to use the unique weapons and powers there. For example, Ruby could be fascinated by the Exotic weapons in Destiny and try to incorporate their technology into her Crescent Rose. Another plot could involve the Guardians from Destiny being sent to the RWBY world to help fight against the Grimm. They would have to adapt to the new environment and team up with the RWBY characters. The third idea is that a powerful enemy from the Destiny universe somehow crosses over to RWBY's world and the combined forces of both universes have to stop it.
Maybe the Persona users' powers start to malfunction in the RWBY world due to the different nature of the place. So they have to figure out how to control their powers again while also helping the RWBY characters in their battles. The RWBY characters could be intrigued by the Persona powers and try to learn from them.
A possible plot is that a portal opens between the Doom universe and RWBY's. Some of the Doom demons start spilling into Remnant, the world of RWBY. Ruby and her team initially mistake them for a new, extremely powerful type of Grimm. As they try to fight them, they realize they need different strategies. Meanwhile, the Doom Slayer follows the demons through the portal to stop them. Eventually, the two groups meet and learn from each other's combat styles to defeat the invading demons.
Maybe the Omnitrix gets malfunctioning and starts to attract Grimm. The RWBY team has to protect Ben while he tries to fix it. During this time, they could learn about each other's powers and cultures. Ruby might be fascinated by the different alien forms and how they can be used in combat, and Ben could be impressed by the Dust - based technology of RWBY's world.
One interesting plot idea could be that the Joker somehow gets transported to the RWBY universe. He might start causing chaos in Vale, tricking the villains and heroes alike. For example, he could convince Roman Torchwick to do his bidding in a more extreme way, which would then draw the attention of Team RWBY. Another idea is that he teams up with Cinder Fall, but his chaotic nature eventually causes their alliance to crumble as he doesn't follow her grand plans in the way she expects.