Other than the Scrappy on Miltank:
No Guard works to where your Pokemon and its opponent never have to do Accuracy/evasion checks. So if you are facing off against a pokemon that abuses Evasion and accuracy dropping attacks, then this ability ensures that you never miss no matter what attack you use.
Its double edged as your opponent gets the same advantage but on a Pokemon like Honedge and Doublade I think it'll be more beneficial than detrimental. But no it doesn't change type effectiveness. If any other Pokemon were to use Normal, Fighting or Poison attacks you'd still have been immune to it.