I dual main ganon g+w and playing from both sides I feel its pretty firmly in ganons favor. They both edge guard each other hard, but I believe if a ganon is patient he actually wins neutral. No good ganon is going to simply just run up commit with a fair, the most they'll do is safely back air your shield and watch what you do afterwords and look for patterns.
The best advice I can give to deal with ganon I'd say is try to always be under him. Bacon under platform and carefully watch to see if it'll disrupt his movement or hit him and go for a less committing option such as down air, waveland jab, or short hop nair under platform.
Being above him is the worst thing you can do, try to limit your jumping as much as possible and keep your ground with spacing mixup distances short hop bacons.
If you feel really like you need to approach, I highly suggest you view it as movement based as possible rather than a movement option. Try to out maneuver your way through ganon and put pressure on him with your spacing with the goal of punishing his mistakes. I highly suggest always being aware of the aeriel side b range and keeping insight on always being able to make a simple dashing wavedash to be just out of it just in case. Ganon will try to condition you with it, so be very careful.
If the ganon is committing, it should be very easy. That video you linked the ganon made infinite mistakes and if you had more control of your movement, he would have been a cinch to punish them. You still really need to learn your punishes as well, against a character like ganon a common string after a grab should lead into down air pillaring or at worst case an up air up b up air/fair/nair/sideb. You are trying to finish your punishes way too early and are not utilizing the combo potential that is up b with good di understanding.
I think instead of worrying about the matchup, you should really focus on figuring out some fundamentals with your character. Game and watch commits very strongly with a lot of his non bacon options in neutral if you aren't careful, and experienced players will tear you apart for it. Try and watch their character and just react to it, you'll get better much faster and his reactionary neutral game will make more sense.
Edit: I also thing small stages are good for g+w in this matchup, but thats at a higher level. Just go wherever you're comfortable with.