Although I do not use terrakion in my team, I don't really see why it may be considered broken in this meta. Yes it is powerful but it can also be quite easily crippled.
DO NOT BAN Terrakion
When I tried to comment a screenshot it didnt show up for some reason, so instead I attached it as a png, and alternatively here is the link to it:
https://imgur.com/a/21jA8
Not gonna make you force you to change your opinion, but...
It's possible to cripple it, but that's theoretically possible with anything. Sure, I can go ahead and paralyze Rayquaza-Mega with prankster Thunder Wave, but that doesn't make it any less ridiculous.
As a better example, it's definitely possible to, say, Thunder Wave or Will-O-Wisp Terrakion. But doing so requires either you to A) Be Prankster, B) Be one of the, like, 5 things that can take less than 90% from Close Combat or Stone Edge and have Twave/Will-O, or C) Being Aegislash. Unless you want to remove creativity on your team and go run one of the selective checks that might be able to cripple Terrakioin, good luck. And if they're a faster threat able to check offensively, have fun getting Edge'd by the Scarfed set. And Substitute sets can beat Twave/Will-O if you aren't prankster as well, and result in a free Close Combat or Swords Dance.
As a note though, since I barely play this meta and don't care for where it goes for the most part, I'm not gonna go ladder for reqs.
Am happy about the suspect though, I used Tinted Lens rather than Adaptability for a bit, then went to Adaptability, and it's super busted.
then you walk into Head Smash Reckless Terrak in AAAS or one of the many sets with stuff like Ice Hammer for Lando and cry
pls ban
minutes later edit: or doublade but I don't like Doublade.