Another possible ending is that Gohan sacrifices himself to defeat Cell. He could use a self - destructive move that not only takes out Cell but also costs Gohan his life. This would be a very dramatic and tragic ending, but it would also show Gohan's selfless heroism.
One possible plot could be that Thanos somehow gets his hands on the Dragon Balls. He wishes for the power to snap away half of all life in the universe even more easily. The Z - fighters sense this great imbalance and travel to the Marvel universe to stop him. Goku, being the most powerful Z - fighter, tries to fight Thanos but quickly realizes his strength is different from what he's used to. Vegeta might have to team up with Iron Man to come up with a technological way to counter Thanos' Infinity Stones while Goku trains to reach a new level of Super Saiyan to take on Thanos directly.
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.
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.
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.
It's hard to say for sure, but Goku would be a very strong contender. His ability to keep increasing his power level through training and reaching new forms like Super Saiyan God and Ultra Instinct makes him extremely powerful. However, characters like Franklin Richards in the Marvel universe have reality - warping powers that could also be very hard to defeat. But if Goku were to fully master Ultra Instinct and combine it with the power of the Dragon Balls, he could potentially be the most powerful.
One interesting match - up could be Goku vs Liu Kang. Goku is known for his incredible strength and speed, while Liu Kang is a highly skilled martial artist with fire - based powers. Another great match - up would be Vegeta and Scorpion. Vegeta's prideful and aggressive fighting style against Scorpion's vengeful and stealthy attacks would make for an exciting fight. Also, Piccolo vs Sub - Zero could be cool, as Piccolo has his energy attacks and Sub - Zero has his ice powers.
One aspect that fanfiction might focus on regarding Videl is her growth as a fighter. Since she was introduced as a strong - willed martial artist, fanfictions could show her training harder and achieving new levels of strength. For example, she could be part of a new tournament storyline where she faces tougher opponents and learns new techniques.