The autolink angle is a special knockback angle programmed into certain attacks in Brawl and Smash 4. While it reads in the game data as an angle of 365, 366, or 367 degrees, the game treats it rather differently - instead, targets are sent in whatever direction the attacker is moving.
The angle does not exist in Smash 64 or Melee; attacks with the angle in Brawl have fixed angles in the other two games.