So who would win? As the illustrious Sam Wolfe puts it, "A MORE IMPORTANT QUESTION HAS NEVER BEEN ASKED."
I am inclined to agree.
Note: I am assuming the most iconic of all Link incarnations, the Ocarina of Time. This is also fitting as it is the earliest incarnation in the canonical timeline, pending the release of Skyward Sword.
Now, at first glance the answer may seem objectively obvious. Technologically, Vader is from an indefinite future, while Link is from our medieval past. However, as with any sci-fi/fantasy crossover scenario, one must establish equivalencies.
For example, superhuman power can be attributed to either: Vader with the Force, Link with the combined might of various magical abilities and the Triforce of Courage. Below is a listing of basic superhuman abilities:
Darth Vader:
Force Perception (can sense an opponent)
Force Manipulation (Telekinesis, as seen in the Bespin duel and via Force Chokes)
Mind tricks? Its possible
Note that Vader does not actually have the ability to use Force Lightning, because he has no limbs. Palpatine was able to keep him in check because he had that upper hand, but its also the reason Vader was never able to surpass him.
Here is Link's listing:
Farore's Wind: Teleportation
Nayru's Love: Basic protection
Din's Fire: Frikkin' fire, man!
Magic sword attacks: Sword spins infused with magic granted by great fairies
Navi: The ability to keep track of an enemy and react faster
Tools and equipment:
Vader:
Lightsaber : A laser sword
Vader Suit : A cyborg life support system
Link: Equipment
Master Sword : The Sword of Evil's Bane
The Mirror Shield: A shield capable of reflecting light and beam based attacks
Golden Gauntlets : Gloves that lend him superhuman strength
Hover Boots: Boots that allow him to hover in the air for short periods of time
Link: Items (Link is capable of having three items on hand, as per the C-button mechanic of Ocarina)
Lens of Truth: A looking glass that allows Link to see through illusions
Hookshot: Think Batman's grappling gun
Fairy in a bottle: Basically a second life. Think one up or phoenix down.
Now the item distribution may seem unfair, but Vader himself would disagree. Vader is defined by his ability to navigate any situation with his wits alone. He uses the environment in ways Link doesn't, and relies on his own cunning over a host of tools.
Link on the other hand is defined by his ability to approach any situation with the right tool for the job. That's his thing.
I've got to say though, even without his three Items its looking like Link has this one in the bag. Compare base weaponry, for instance: Vader's Lightsaber is a sword made of lasers. The sort of thing you'd think couldn't be beat. And many of you may be thinking "well that beats the Master Sword easy, right? Lasers vs steel, steel melts!"
WRONG. The Master sword is a very special blade, forged as the key to the Sacred Realm and conditioned to be wielded by only those completely pure of heart. Over the course of Ocarina, we've seen this sword bounce orbs of magical energy back at opponents as if they were tennis balls, we've seen it slay monster after impervious monster. It can be infused with magical energy to take on lightsaber-like qualities: To the people of Hyrule, its the game changer.
So lets go ahead and say that Vader's lightsaber and the Master Sword are evenly matched. If not, the Mirror Shield deflects lasers. That's what it does. That is its function. Link's fine.
What about Vader's mind tricks and such? LENS OF TRUTH. Done.
Now, both are also expert swordsmen, but Link is faster than Vader because he's got real, 100% human parts. He's got the agility for backflips, rolls, side-evasions and jump attacks that Vader can only dream of in memories of Prequel days.
At this point, Vader's main advantage is his force perception. He's able to sense where Link is coming from as soon as Link decides what his next move is. My response to Vader's biggest magical advantage is the Three goddess spells under Link's command. Nayru's love leaves Link impervious to damage, Farore's Wind allows him some basic teleportation, and Din's Fire summons a dome of flame that burns anything in its blast radius. At some point, Vader's weakness becomes the gap between knowing what Link will do next and his ability to react to it.
Finally, Link already has a resume for defeating caped dark lords. I'd call him in on Vader over Luke Skywalker any day.
