A Goten and Harry Potter crossover could also be cool. Goten could be sent to Hogwarts by some magical accident. He would be the odd one out, not understanding the wizarding world at first. But his Saiyan strength could come in handy during the Triwizard Tournament, for example, when facing the dangerous tasks. Maybe he'd have to use his ki blasts instead of magic spells to get through certain challenges.
One idea could be that Goten and Trunks accidentally travel to an alternate dimension where their roles are reversed. Goten could be the more studious and reserved one while Trunks is the carefree fighter. They have to figure out how to get back while also dealing with the differences in this new world.
One idea could be a story where Chichi and Goten go on a training adventure together. They face various challenges and Goten learns important life lessons from his mother.
Perhaps there is a situation where they have to team up to protect the Earth from a new threat. In the process, they discover feelings for each other that they hadn't expected. Their relationship then develops against the backdrop of this high - stakes adventure.
One idea could be Goten traveling back to the Saiyan - Saiyan war era. He could end up changing some small events that have big impacts on the future, like uniting some Saiyan clans earlier. This would create a whole new timeline where relationships between characters are different.
Another option is a crossover with the Pokémon world. The Phantom Thieves could travel to a region in the Pokémon world and discover that someone is using Persona powers to make Pokémon act out of control. They would need to catch Pokémon themselves and use their combined powers of Personas and Pokémon to stop the bad guy. It would be interesting to see how they interact with Pokémon trainers and the whole Pokémon ecosystem.
A cool plot could involve the Persona 5 crew going back in time to the events of Persona 3. They might end up interfering with some of the original events, which could have unforeseen consequences. For example, they could accidentally change the way a key character in Persona 3 awakens their Persona, and then have to figure out how to fix it while also dealing with the Shadows in that era.
One idea could be to cross it with another popular RPG. For example, having the Persona 4 characters enter the world of Final Fantasy. They could interact with the different races and magic systems there. Another could be a crossover with a detective - themed anime. The Investigation Team could team up with the detectives from that anime to solve a mystery that spans both worlds.
Another plot could involve a crossover with the Punisher and the X - Men. Frank Castle might find himself in a situation where he has to work with mutants. He could initially be distrustful but then realize they are fighting for a similar cause against a common enemy that is targeting both humans and mutants. For example, a group of anti - mutant and anti - vigilante fanatics.
One idea could be a crossover with Peter Pan. Tinkerbell could meet characters from another world, like Alice from Wonderland. She might be confused by the strange rules and creatures there, and her magic could interact in unexpected ways with the Wonderland magic.
Another plot could involve a crossover with a post - apocalyptic world. The Boys find themselves in a world where society has collapsed, and they have to team up with the survivors against new threats. This could bring out new sides of the characters as they are forced to adapt to a completely different environment and face challenges they've never faced before.