I thought it ducked under in gen 6 and 7? Maybe not the whole time, but it's definitely become weaker.
If it hasn't went down to UU or BL yet, then it will within the next gen, or maybe the one after, I predict. It's strong, but lots of other mons are stronger. It's bulky, but its typing has a lot of weaknesses. In fact, I feel like it's only OU because there are basically no good defensive Dark-types, really. Bar some obvious stuff like MegaGyara. Nothing to switch into the Ghost, Dark, and Psychic moves that have been buffed so much recently.
Once we get a new decent Dark-type, T-tar is a goner, imo.
