A new, self - created android by Dr. Gero's successor could be the main villain. This android could be specifically designed to target and defeat Super Saiyan Blue users. It could have the ability to absorb their energy and use it against them, making it a very difficult enemy for Goku and Vegeta to face.
One idea could be a story where the Saiyan Blue form has an unexpected side effect. For example, it could start to drain the user's life force slowly but surely. Goku discovers this during a battle and has to find a way to either control it or reverse the effect while still fighting powerful foes.
A Super Saiyan in Naruto fanfiction could be a result of a dimensional rift. Maybe a portal opens between the Naruto and Dragon Ball universes and some Saiyan energy seeps through, affecting a Naruto character. This would be an interesting plot device as it would introduce an alien concept to the ninja world.
One idea could be Gohan in his Super Saiyan 4 form facing a new, powerful enemy from another dimension. He could struggle at first to control the raw power of this form while also trying to protect his friends and family. Maybe this new enemy has the ability to nullify the Saiyan's energy attacks, forcing Gohan to rely more on his martial arts skills that he learned from Piccolo.
One aspect of Dragon Ball Z Pan Super Saiyan fanfiction could be exploring new power - ups for Pan. Maybe she discovers a unique way to achieve the Super Saiyan form that's different from the traditional methods. It could involve her training in a secret place or having a special encounter that unlocks this power.
In a fanfiction, Gohan as Super Saiyan 3 could be involved in a time - travel adventure. He travels back to a crucial point in Dragon Ball Z history and has to use his Super Saiyan 3 powers to change certain events. This could lead to a whole new timeline where things are different. For example, he might be able to prevent the destruction of Planet Namek or save some characters who originally died.
Another aspect to consider is how the Super Saiyan transformation would affect the relationships in the Naruto world. If Sasuke were to gain Super Saiyan powers, it could either drive him further away from Naruto due to the newfound power or bring them closer as they explore the new abilities together. Also, the concept of ki from Dragon Ball and chakra in Naruto could be merged, creating a whole new type of energy for the characters to utilize.
A fanfiction could explore Pan's journey as a Super Saiyan in Dragon Ball GT in relation to her family heritage. She might struggle with the pressure of living up to the Saiyan legacy. Her Super Saiyan transformation could be a turning point where she finally accepts her role and uses her power to protect those she loves, while also learning about the true meaning of being a Saiyan.
Goku is often very popular. Since he's the main character in the Dragon Ball series, many fanfictions focus on his journey with the Super Saiyan 4 form. Vegeta is also a top pick. His rivalry with Goku and his own Saiyan pride make for great stories in the Super Saiyan 4 context. Another popular character could be Gogeta, the fusion of Goku and Vegeta. His Super Saiyan 4 form in fanfiction can be extremely powerful and is often used to face off against the toughest of foes.
In Dragon Ball Super Super Saiyan 4 fanfiction, often there are concepts about alternate universes. Picture a universe where Super Saiyan 4 is the norm rather than an extreme form. This could lead to different power hierarchies and battles. Additionally, some fanfictions explore the idea of Saiyan - human hybrids achieving Super Saiyan 4 in unique ways, perhaps with abilities that are a blend of human ingenuity and Saiyan strength.