Bulma has played a huge role in the story since her first episode, being the first friend Goku ever has and agreeing to gather all the Dragon Balls with him. The timeline of Future Bulma has endured a lot of devastation, as anyone keeping up with Dragon Ball Super is aware of. We won't go into the specifics, but Bulma is definitely the character most used for "fan service" throughout the franchise. Bulma was pretty young at the start of the franchise, so her desires weren't exactly the most selfless at the time either. For a show marketed for children, the original Dragon Ball series had a lot of sexual under and overtones.
That's certainly true of the franchise's longest running character.
And if Battle of Gods happens inthat puts her in her mid-forties. Xuanzang is more of a guide on the quest, and has to surround himself with warriors to protect himself. As the years went by, Goku became physically stronger, while Bulma's strength was her mind and the many brilliant inventions she produced. Before Goku became the first Super Saiyan in modern times, the Z Fighters based their understanding of the transformation on legends. The unifying story in the Battle of Gods movie was the characters coming together to celebrate the birthday of Bulma. The go-to source for comic book and superhero movie fans.