In Japan, it is believed that your blood type can tell much about you. That's why many anime and video game characters are given blood types. Of course, we don't know Link's true blood type because Ninty likes to withold information about Link in general. So I shall speculate and comment on each type of blood and whether or not its characteristics would fit Link.
Type A blood types are defined as farmers. They are considered conventional in all that they do. They are considerate to other people, and find it hard to tell lies. Loyalty towards friends and co-workers is another trait. On the downside they can be secretive. This means they don’t often share their feelings, and can become insecure and pessimistic. Apparently, once they’ve had a few drinks they can turn into nasty pieces of work.
Probably the best match, I'd say. I wouldn't define Link as conventional, but he is considerate and very loyal. He never shares his feelings...he never shares his opinions, either. I assume he wouldn't lie, or would do very little of it. And I've never seen him drunk, so I can't say much about that. ;)
Type B blood types are defined as hunters. Contrary to Farmer types these people are non-conventional, and care little for other people’s opinions. This makes them thick-skinned. This doesn’t mean they are uncaring. Indeed, they are extremely passionate about things dear to them. The negative side to their personality is that they can seem shallow to other people, and lazy, because they might not do what other people request. If they don’t get their own way they can seem impatient.
I'm sure Link does respect others' opinions and would listen to them. He's definitely not lazy or shallow, and he always does what is requested of him. Patience...it only took an hour for King Zora to scoot to the other side of the cavern entrance, but Link stood quietly. Basically, no. This doesn't look like a good match.
Type AB blood types are considered humanists. They are quite rare. They go with the head rather than the heart. They like accord among people, and therefore play a good role as a mediator within a group. They are also good with money. Unfortunately, with trying to please everyone, they can seem to be two faced.
Probably the worst match. The only thing I can see is maybe the part about being a mediator.
Type O blood types are defined generally as warriors. This is perhaps because Type O is the oldest of all the blood types. These people are highly motivated, leaders of people. They aren’t afraid to gamble because they are confident they can pull it off. They have a strong physical presence and are generally good at sport. However because they are leaders they can often be seen as status seeking, and obsessive in their quest for success. This obsession can also make them seem boring to other people.
Hmm...not bad. Highly motivated, a leader not afraid of taking risks. I don't know if I'd say he has a strong presence, but I'm sure he's good at sport. I also wouldn't call Link obsessive, just..."highly motivated" was a nice term.