^Shadow Chandy means that Excadrill now has no counters, as they are all killed by chandelure. Shadow Chandy now means that Latios no longer has any counters who aren't named Tyranitar...as they are ALL killed by Chandelure.
Oh by the way. Were you planning on using celebi, tangrowth, ferrothorn, jellicient, skarmory, bronzong, jirachi, etc, as your wall of choice? That's wonderful. Have fun using shed shell on every last one them. Using Gastrodon, quagsire, or swampert to counter thundurus? What are you talking about? How are they going to be countering anything when they get picked off by a chandelure energy ball? And before blaziken was banned, slowbro was his only counter? Ha! Chandelure.
And this is barely scraping the surface of what shadow tag chandelure can do. In the hands of a bad player, you'll probably only see it kill one pokemon and then get revenged by your pursuit tyranitar. In the hands of a good player, it does a much better job that wobbufett ever could dream of doing at picking off anything that could easily get in your way. This is a huge deal for pokemon like latios, whose "counters" and checks do not threaten chandy at all whatsoever.
edit: and it's speed sucks compared to many common sweepers that would revenge it, and if it has a scarf then you can pick a pokemon to easily dispatch it the next turn
In the dreamworld tier, you had breloom randomly tossing out stone edges instead of killing the excadrill in front of him with a technician mach punch. I've seen Scizor carry night slash. Choice Band Night slash. And that is only for chandy's trap/revenge set. Ever had a subCM Chandy double switch onto your Blissey as you attempted to wall something? Oops. Unlike Magnezone, this thing probably won't stop at only killing two pokemon. Better hope tyranitar and heatran are still alive, or that chandy wasn't carrying flame charge so that it could avoid being revenged.