This is short and simple. I myself have not had many problems with Shadow Tag in Inverted. I know it isn't the most alive tier, but that doesn't change the fact that when something is broken, it's broken. My opponents on the other hand seem to have a lot of trouble once my Shadow Tag Gothitelle is in on their Avalugg or Porygon2 for example. It's easy to trick a Choice Scarf on a variety of Pokemon then manage to set up with Calm Mind & Rest. I've been playing the tier and am currently a gym leader for it and I, a user, am proposing something be done about this.