The self - insert character could be an alien with the power to manipulate energy in a different way than the characters in Dragon Ball Z. They are drawn to Earth because of the powerful ki signatures there. Once on Earth, they get involved in the fight against the Androids. They use their unique energy - manipulation skills to disable the Androids' power sources temporarily, giving the Z - fighters an advantage in the battle.
Perhaps the self - insert character is a Saiyan - human hybrid from a future timeline. They arrive in the main Dragon Ball Z timeline just before the Saiyan saga. They have knowledge of future events which they use to train the Z - fighters more effectively. For example, they could introduce new training methods inspired by techniques from their own timeline. They also form a special bond with Goku as they are part Saiyan, and together they face challenges like Vegeta's arrival on Earth.
One idea could be inserting yourself as a new Saiyan on Earth. You could train with Goku and the gang, learn their techniques, and face off against the villains. Another idea is to be a scientist who creates new power - up devices for the Z - Fighters. Maybe you discover a new form of energy that gives an edge in battles.
One idea could be to insert yourself as a new Saiyan character. You could have unique powers, like the ability to control a new type of energy. Maybe you arrive on Earth during the Tournament of Power and form an unexpected alliance with Goku and the others. Another idea is to be a non - Saiyan with a special gadget that can nullify ki attacks, which would create really interesting battle scenarios in the Dragon Ball Super universe.
Often, the self - insert character is from Earth and has to deal with Beerus' view of Earthlings as weak. So they strive to change his perception. Maybe they introduce him to Earth's culture beyond just food, like our music or art. Another plot point could be the self - insert getting involved in Beerus' dreams or nightmares. Since Beerus is a powerful being, his dreams might have some sort of impact on the universe, and the character has to figure out how to deal with it. There could also be a situation where the self - insert character teams up with Whis, Beerus' attendant, to keep Beerus in check or to help him with a particular task.
One idea could be that your self - inserted character is a long - lost Saiyan who has unique powers. For example, the ability to control time on a small scale during battles, which would add a new dynamic to the fight scenes in the Dragon Ball Hero universe. Another plot could involve your character being from a different dimension and having to adapt to the rules and power levels of the Dragon Ball Hero world while also trying to find a way back home.
One interesting plot could be a new villain emerging from a long - forgotten dimension. This villain has powers that are a mix of different techniques from all the universes in Dragon Ball. He starts causing chaos by stealing the energy of strong fighters to open a portal to an even more powerful realm.
Another interesting plot could be that the gamer aspect brings in virtual reality elements. The Z - fighters enter a virtual world where they have to fight enemies with different rules. This virtual world could have power - ups and obstacles that are based on video game concepts, like finding hidden keys to unlock new areas or defeating bosses to gain special abilities that they can then use in the real Dragon Ball Z world.
One idea could be a crossover with the Naruto universe. Goku and Naruto could team up to fight a common enemy. Maybe they face an evil villain who has the power - stealing abilities like Cell and the ability to use powerful ninja jutsus. Another plot could be a crossover with One Piece, where Luffy and Goku have a friendly competition about who can eat more food and then end up having to work together to defeat a new threat at sea that has the strength of Saiyans and the deviousness of pirates.
Perhaps a fanfiction where a young Saiyan from a destroyed planet manages to find their way to the Xenoverse 2 world. This Saiyan has a different fighting style compared to the ones we know. They join the Time Patrol not just to save timelines but also to find a new home for their kind. Along the way, they face discrimination from some of the other races in the Xenoverse due to their Saiyan heritage, but they prove themselves worthy through their strength and determination.
One idea could be Goku Jr facing a new, powerful enemy that has a unique power related to time manipulation. This would force him to train in ways he never has before and seek help from unexpected allies, like some of the older, wiser characters from the original Dragon Ball Z series.
Well, a plot could be Android 21 somehow getting her hands on the Namekian Dragon Balls. Since she has that scientific mind, she might try to figure out how to modify the wishes. In the process, she could draw the attention of Frieza who wants the Dragon Balls for his own evil purposes. Then the Z - fighters would have to step in to protect Android 21 and the Dragon Balls. Another plot idea is that Android 21 is from an alternate universe where she was created by the good guys. When she crosses over to the main Dragon Ball Z universe, she has to adjust to the different power levels and politics among the characters. And she could end up being a key player in the fight against Buu, perhaps using her unique abilities to weaken Buu in some way.