Well, the first time I tried to beat him (after the castle is destroyed), I was using the Biggoron sword the whole time, even after the cutscene. I kept on hitting him for like 10 minutes, eventually running out of arrows and magic, and having to resort to the hookshot and bombs and stuff, which is not easy. I died, and didn't play for a while. But a couple months ago, I tried again with the master sword and beat it fairly quickly.

My question is, can you beat Ganon with the Biggoron sword or do you have to use the master sword?

You have to use the Master Sword once you've regained it. Anything else won't work.

You don't need to use arrows by the way, either. You can just roll under his legs to get behind him.

the arrows just waste precious magic which u can use to make that specail sheild thing thats how i beat him also u can use the megaton hammer to fight hi before you get the master sword back

Or the Biggoron's Sword