nice cocept
So, let's start with the bad things since they are very few and not so much important:
1) The animation and the drawings could be better. Not that i can do better, but it is clear enough that more experience in flash animation could have done a better job.
2) The concept of two epic rivals finding out their FINAL POWAAAAARZZ is not very original.
Now with the good part of this video:
Ocarina of Time gave us a better insight on ganon's power. If he holds part of the triforce, that explains perfectly why he keeps coming back. It is also rational to think that the only opposing force to a demi-god is another demi-god, therefore, Link have another part of it. Where I'm going with this? Once link found his own true power, he should be evenly matched with ganon, however, he won in a single blow, so how is it even possible?
First option, Link's triforce is stronger than ganon's. Very unlikely if the three of them makes a balance.
Second option, Link is stronger than ganon. WHY just because a fairy boy has a power level OVER 9000 times the guy who is considered "The king of evil". Also very unlikely.
Third option, and easier to believe: Link has more battle expertise than ganon/dorf. This is more logical and is clearly shown along the whole video. Ganon keeps teleporting and throwing things (dark balls, skulls, etc) or simply blocking with pure dark energy while link moves around makes his way over ganon attacks and manages to hurt him while being obviously handicapped on the fight (Jumping around vs flying, wooden boomerang vs DARK MATTER, etc)
Link obviously shows the best skill at fighting, and this video makes it easier to beleive that if both of them holds the exact same power, it would take only a few seconds to shatter ganon in pieces.
Also, I don't know if i made this clear, but even if the animation was not the best one, the concept of every part on the fight was Awesome (take note on the capital A for Awesome). It really shows a dynamic fight where there is no time to breath and think, a fight where link had to stay struggling constantly and finding new ways to overcome ganon powers.
So, final reviews (also, TL/DR) 8 out of ten because the concept of the video was awesome, the fight itself was well planned but there is a small lack on the animation/drawing part, and the originality part.