It's not like SpD Milotic walls Darmanitan very well in the first place...
But honestly, Gothitelle is really not as brainless as people are making it out to be. Now, I'm not saying a well played Gothitelle isn't absolutely destructive, but so is a well played Mienshao / Chandelure / Kingdra / Raikou / Roserade / whatever. The problem--imo--lies with how insanely difficult it is to play around Shadow Tag without decreasing the quality of play in the tier as a whole (i.e. running fucking Shed Shell on everything).
The insanely offensive nature of the tier at the moment makes it hard for me to call Gothitelle "broken" in the traditional sense. But one thing I can say for certain--it distorts the tier a hell of a lot. Is it a good distortion? I doubt it, but I can't say for sure. However, if I determine it is indeed a change for the worse, I'll probably vote to ban it when the time comes.