One idea could be to focus on Bardock's perspective before his fateful battle. Maybe explore his thoughts about his son Goku being sent to Earth and his own impending doom. He could have some premonitions about Goku's future role in saving the universe.
Definitely include Bardock's last stand. His heroic yet doomed battle is a crucial part of the Saiyan lore. It could be written in great detail, with Bardock using his full power against Frieza's forces.
In a 'Goku Saves Naruto' fanfiction, Goku might teach Naruto some of his unique fighting techniques. Since Goku has such a vast knowledge of martial arts and energy control, he could help Naruto become even stronger. For example, he could show Naruto how to better control his chakra using the principles of ki control. And also, Goku's fearless attitude in battle could inspire Naruto to face his enemies more bravely. Goku could also use his Dragon Balls to wish for something that would benefit Naruto or his village, like restoring the damage done by a powerful enemy attack.
It could be someone like Madara Uchiha. He's extremely powerful and his goals are often in conflict with Naruto's. Goku would have to face his Sharingan abilities and his vast array of jutsu.
There's a fanfiction where Tien and Yamcha are transported to an alternate dimension. In this dimension, they have to fight against versions of themselves that are evil. It's a really cool concept as it explores different sides of their characters and how they deal with seeing their own dark counterparts.
One possible fanfiction could be about Tien and Yamcha teaming up for a special training session. They might start off with some friendly sparring, showing off their unique martial arts moves. Tien could use his multi - form technique, while Yamcha demonstrates his Wolf Fang Fist. As they train, they start sharing stories about their past battles and how they've grown as warriors. Eventually, they come up with a new combined attack that could be used against future threats.
I haven't actually read this specific 'piccolo and gohan lemon fanfiction', but generally, in fanfictions involving these two characters, it might explore their relationship in unique ways. It could be about their friendship evolving, or perhaps their teamwork in new and unimagined scenarios within the Dragon Ball universe.
A major theme is identity. Since she is a female version of Piccolo, she has to come to terms with who she is compared to the original Piccolo. Family also plays a role. In some fanfictions, she might be searching for her family or creating a new family of her own. Additionally, the theme of good vs. evil is common, as she battles against various villains.
I'm not that familiar with the specific 'Brian Piccolo Thanksgiving Day story'. Maybe it could be about how he spent the Thanksgiving Day with his family, sharing a big meal and giving thanks. It might also involve some special traditions he had on that day.