Not going to say SR actually. I know it's seen as necessary on any team, but lol, I've won plenty of matches without getting SR down or with teams that dont have SR on them, and ive actually found that not throwing in an otherwise bad Pokemon (lead azelf, aerodactyl, etc) just for the sake of getting SR up can be helpful. SR is obviously very good, but as lo9ng as my opponent isn't carrying 6 sashers or a salamence, ive never really missed it. Of course, i normally dont use things that rely on SR for KOs so im biased.
Best move is either Draco Meteor or Outrage. It beats basically everything that isn't a steel or, in draco's case, blisslax (lolsnorlax). Dragon is such a great attack type and the extra power is amazing. Garchomp was banned because of Outrage and Latios was banned in part because of Draco Meteor. Honestly, whenever Salamence comes out, it scares me way more than somebody getting SR and a layer or two of Spikes down. At least you can spikes-proof your team and make it good (and by that i dont mean the ENTIRE team), but you basically need an army of bulky steels and/or walls to take those hits over and over. It's insane lol