I forgot you haven't played in a while. They're discussing whether to ban Gothitelle, Gothitelle and Gothorita, or Shadow Tag as a whole from OU last I heard. There's a really stupid stall team that's running around abusing Gothitelle, I'll see if I can find more on it.
I have already seen what you're talking about (the core of Sableye + Scarf Gothitelle). I think in that case it is uncompetitive by nearly guaranteeing it executes correctly. The argument that Shadow Tag removes any possible counterplay was already the main point for its uncompetiveness, but the fact that core does so to perfection only cements the argument.
Wobufett is debatable though. I use it and like it for its use /if/ done right. Wobuffet is not uncompetitive because it takes correct execution and can be prevented if played right. From what I've heard, there is no way to do this vs Goth and Sableye.
God, my favorite thing to do was get Wobbs behind a sub with Lopunny. Counter and Mirror Coat are ridiculous when you're bouncing back damage from hard hitters without taking a single scratch.
Too bad Wobbs + Tyranitar is a dead giveaway on team preview. I can see people falling for it tho since Wobbs is pretty uncommon.