So! As you're probably aware, Link has the ability to become a wolf. But just what, exactly, does that mean? Well, there are two main points to consider:
Senses and Scents
Link's biggest power as a wolf is his enhanced sense. When he presses the
button focuses his senses, he can see things that are invisible to the naked eye. Ghosts, for example! And places where digging in the dirt will unearth something good. So if you have a character who can become invisible, let me know (if you would be so kind) whether or not wolf-Link is allowed to see them anyway.
Also, Link can track scents with his enhanced senses! In the game he can learn a smell and then see it as a colored trail floating in the air. That's... all I can think of to say about that.
Animals and People
When he's a wolf, Link can talk to animals! All animals -- he's shown to talk to cats, dogs, chickens, hawks, squirrels, monkeys, even frogs! And the curious thing is that none of these animals are the least bit afraid of this big old wolf. One squirrel is quoted as saying that he "smells like the trees of Ordon", and several others can tell that he's Link because he smells the same.
Obviously, it's your choice whether you want your animal character to be terrified of him or not! But if you want to recognize that he's not a threat -- or even recognize that he's Link -- the option is there. (Note that Link is used to animals not being afraid of him, so he will trot right up to you and say hello. :D)
Meanwhile, almost all the humans in the game are terrified of wolf-Link, so he avoids people as much as possible. It'll take him a while to get used to the fact that not everyone here is afraid of wolves.
Animal speech is represented by green text in the game, so when wolf-Link speaks, it'll be in green, to represent the fact that only animals (or Dr. Doolittle-type humans) can understand him. Edit: As far as animals that don't have canon voices, I'm fine with however you want to respond! Actual speech or just implying that something gets across through actions. Whatever you're most comfortable with is A-OK by me.
And I believe that's it! Woo, that wasn't as long as I thought it was going to end up being. \o/