It could be a genetic mutation in the fanfic's storyline. Some strange event or factor could have caused a change in Bardock's genes, making it possible for him to become Super Saiyan. This genetic change might be related to some ancient Saiyan lore or a new element introduced in the fanfic's universe.
Another plot could be that a mysterious entity bestows the power of Super Saiyan Blue on Naruto. He then has to keep it a secret from his friends and village while also using it to protect them from a new and powerful enemy. This would create a lot of internal conflict for Naruto as he tries to balance secrecy and heroism.
One great Super Saiyan Blue Goku crossover fanfiction is 'Goku in the DC Universe'. It's really exciting to see Goku interact with Superman and other DC heroes. He has to adjust to the different power levels and rules in that universe.
Sure does. Goku attains the perfected SSJB in the manga during intense battles and as part of his power-up journey. It's a significant moment for his character development.
The change of Bardock becoming Super Saiyan in the Vegeta fanfic can completely rewrite Saiyan history. It could start a new era of Saiyan pride and power. Bardock, with his new - found Super Saiyan form, might be able to teach the younger Saiyans about the transformation. This could lead to a more united Saiyan race, as they all work towards achieving the Super Saiyan state. It might also mean that they are not as easily defeated by Frieza, as they have a stronger force to oppose him. This could result in a different galactic power structure, with the Saiyans being a more dominant force.
Well, it could be a really wild and interesting concept. Imagine Naruto with the power of Super Saiyan Blue. He would be incredibly strong, his speed would be off the charts. His rasengan might even take on a blue glow and have the explosive power of a Saiyan attack. Maybe he could also fly around the Hidden Leaf Village like a Saiyan, which would surely shock all his friends and foes alike.