One way to make it unique is by exploring their different origins in the fanfiction. Superman is from Krypton and has his alien heritage, while the Powerpuff Girls were created in a lab. What if there was some connection between their origins? For instance, the same chemicals that created the Powerpuff Girls were actually related to some Kryptonian technology. This would add a whole new layer to their meeting and potential partnership.
A unique story could involve a role - reversal. Instead of Superman being the experienced hero, the Powerpuff Girls are the ones who know more about a particular threat in their city. Maybe there's a villain that uses a type of kryptonite - like substance that only the girls know how to handle. So, Superman has to rely on them for help. This flips the typical dynamic of the more powerful and experienced hero coming to the rescue.
In fanfiction, if The Powerpuff Girls met Superman, there could be an epic battle at first. The Powerpuff Girls are used to being the top defenders in their city, and Superman is a powerful hero. But then they might realize they have a common goal of protecting the innocent. They could team up and use their combined powers to face a huge threat like an alien invasion. Superman's super strength and flight, along with the Powerpuff Girls' unique abilities like Blossom's ice - breath, Bubbles' sonic scream, and Buttercup's tough fighting skills, would make them an unbeatable force.
One possible plot could be that Mojo Jojo discovers a new form of hypnosis and uses it on the Powerpuff Girls. He manages to make them believe they are his minions at first. But then, Blossom starts to break free from the hypnosis using her intelligence and realizes what is happening. She then tries to free her sisters Bubbles and Buttercup, and they all team up to defeat Mojo Jojo once again.
Tickle fanfiction about The Powerpuff Girls can be really creative. It might involve scenarios where the Powerpuff Girls are in a ticklish situation, perhaps during a battle with a villain who discovers their ticklish spots and uses it to try and gain an advantage. However, it's important to note that this kind of fanfiction is more on the light - hearted and fun side of the fandom.
One night, the Powerpuff Girls were flying back to their home after a day full of adventures. They saw the moon shining brightly. When they reached home, they quickly washed their faces. Then they got into their beds. Blossom covered herself with a pink blanket. Bubbles snuggled with her doll. Buttercup just closed her eyes. They thought about all the good they did that day. And within minutes, they were fast asleep, ready for a new day of saving the world.
Mojo Jojo is a likely villain. He's always trying to outwit the Powerpuff Girls, and hypnosis could be his new devious plan.
The plot could be that Mojo Jojo uses a new device to hypnotize the Powerpuff Girls. He makes them do silly things like dance in the middle of the town or speak in a strange language. Then the Professor has to find a way to break the hypnosis.
One plot idea could be that a new villain has a tickle - ray weapon and targets the Powerpuff Girls. They have to figure out how to avoid getting tickled and defeat the villain at the same time.
One idea could be that the babysitter has to deal with the Powerpuff Girls when they accidentally get hit with a reverse - aging ray. So instead of being their usual powerful selves, they are like toddlers with their powers going haywire. The babysitter has to keep them safe while also trying to find a way to reverse the effect.
Perhaps the older sister in the fanfiction is an outcast among the Townsville citizens because of her more mysterious powers. The story could revolve around her trying to gain acceptance while also helping the Powerpuff Girls deal with their regular battles. For example, she might have the power to communicate with spirits and uses this to gather information about the villains' plans.
Mojo Jojo would be a likely main antagonist. He's always trying to outwit the Powerpuff Girls, and using hypnosis would be just another devious plan in his arsenal.