Link is one of my favorite characters of all time, and this time he is based on his incarnation in Breath of the Wild. Princess Zelda instead was based on A Link Between Worlds.
He hasn't changed too much. He still has his trusty (and unbreakable) Master Sword and Hylian Shield. I didn't notice it in the other games, unless this was the first, but his shield can stop any light projectile attack if faced in the right direction.
The biggest change with Link is this new blue tool. Straight from Breath of the Wild. But it is harmless to the other player unless you choose to let it go off.
And it can be a real pain if you're playing against Link. Though better players smack that blue orb away like it was a ball of paper. So it can sometimes be a curse than a blessing.
His Final Smash is a powerful arrow attack. It's got its power, but you have to aim your Final Smash carefully. I've missed several times myself.
Like always when Kirby absorbs Link, he gets the cute green Hylian hat and Link's bow and arrow. Not the greatest power Kirby can get, but useful.