Disclaimer: I do not own Dragon Ball Z, or Naruto. They are owned by Akira Toriyama and Masashi Kishimoto respectively. I do not claim to own anything in this story.
"Hello, viewers," Kakashi greeted, starting off the episode as he usually does. "Welcome back to Piccolo and Kakashi on Theories. Today, we'll be returning to the Dragon Ball series to answer a question some fans have been asking for a long time...what if Vegeta turned Super Saiyan 3 during the events of the Buu Saga?"
"This one is simple. How we'll do this is we will take different points in the saga and see how they would change if Vegeta had the ability to turn into a Super Saiyan 3," Piccolo explained further. "First of all, the tournament would stay the same as Vegeta never even transformed into a regular Super Saiyan during that time, so Super Saiyan 3 is out of the question there."
"After that, there's the bit with Babadi and his minions, which would again be the same as it was before, except Majin Vegeta could possibly be a Super Saiyan 3. This would mean that the fight between Goku and Majin Vegeta later on could be somewhat more epic in that regard," Kakashi added.
"When Majin Buu is unleashed, Majin Vegeta would likely go take him on as he normally would; except for the possibility of him actually beating Buu in his Super Saiyan 3 state. If that were to happen, Babadi's death would soon follow and the entire series would end there until Dragon Ball Super's storylines happen, which would not be affected at all as Super Saiyan 2 and 3 were both made irrelevant by the advent of Super Saiyan God. Killing Babadi would likely bring Vegeta back to his original state."
"If Vegeta still died at the hands of Buu, the events of the story would play exactly the same way, except Super Saiyan 3 Vegeta would definitely be a great help against Kid Buu. A Spirit Bomb may not even be needed and if Goku and Vegeta fuse with the Fusion Dance, Super Saiyan 3 Gogeta would surely be able to best Buu."
"So overall, not much would change. Vegeta may try to train in Super Saiyan 3 and might even be able to master it, similar to how Goku and Gohan mastered the original Super Saiyan form in the Cell Saga, but would probably not succeed as not even Goku was able to master the form and he was the one to discover it. It seems like the Super Saiyan 3 form itself is rather unstable and should only be used as a last ditch effort - if Super Saiyan 2 won't cut it."
Kakashi paused. "You Saiyans and your crazy transformations. It's because of Super Saiyan 3 and Super Saiyan 4 that fan-made forms like Super Saiyan 5 exist. There's even a Super Saiyan 100!"
"There is?" Piccolo asked, intrigued. "It's not like your fanbase isn't crazy sometimes either. Need I remind you of what is on that particular fan-fiction website?"
"You got me there," Kakashi shrugged. "Anyway, that's all we have to say. Piccolo and I will see you all next time."
The episode ended, allowing the two presenters to leave and for the crew to work on getting the episode to a releaseable state.