There are no such inappropriate 'Straight Shota' stories in the official Dragon Ball Z canon. Dragon Ball Z mainly focuses on epic battles, power-ups, and the adventures of Goku and his friends to protect the Earth from various villains.
One alternative is to focus on character backstories. You could write about the early days of Piccolo, how he came to be the way he is. Another option is to do crossovers with other non - sexual universes. Maybe a story where the Dragon Ball Z characters meet characters from a magical anime world and they have to work together to solve a problem. Also, you can write about the relationships between the characters in a platonic way, like the deepening of the friendship between Gohan and Krillin.
The full story of Dragon Ball Z is about Goku and his friends protecting the Earth from various powerful villains. It starts with Raditz arriving on Earth, revealing Goku's Saiyan heritage. Then there are battles against the Saiyans like Vegeta and Nappa. Later, the threat of Frieza emerges on Namek. Goku transforms into a Super Saiyan for the first time to defeat him. There are also the Androids and Cell arcs which bring new challenges.
One interesting crossover could be a battle between Hulk's brute strength and Goku's Super Saiyan power. Maybe in the fanfic, they start off as rivals, with Hulk misunderstanding Goku as a threat to Earth. Their fight would be epic, with Hulk's limitless rage against Goku's increasing power levels. It could also explore how their different universes' power systems interact.
Dragon Ball Z is both anime and manga. The anime was adapted from the manga and they share the same story and characters, but presented in different mediums.
A Kryptonian in the Dragon Ball Z universe could potentially be a very powerful addition. Their natural abilities like super strength, flight, and heat vision could make them a force to be reckoned with. However, they would also face challenges as the Dragon Ball Z world has its own power scale with ki-based powers. They might have to adapt to the different fighting styles and power sources. Maybe they could learn to use ki in addition to their Kryptonian powers, or they could find a way to combine the two in unique ways.
Well, for a Dragon Ball Z fanfic to be good, it needs to have engaging action scenes. Since the series is known for its epic battles, the fanfic should be able to capture that same energy. It also helps if it has some unique elements, like introducing new forms of the Saiyans or new power - up techniques that fit within the Dragon Ball Z lore. Another factor is the pacing; it shouldn't be too slow or too rushed.