I think we should all look objectively at these three pokemon for the following discussions: Kingdra, Excadrill and Dragonite. I think everyone knows what the former two are mentioned there (meta defining, etc.) but I'll expand a bit on Dragonite. Dragonite is the essence of quintessential Dragon, perfect ability for any of it's roles (phazer, tanks, sweeper, bander, mixed, set-up, etc.), Priorities, massive widepool, all around excellent stats (and the only average stat, speed is boosted by Agility and Dragon Dance) that you will be pressed hard to find a reason not to use this fat dino on your team. From the moment he got Multi Scale he basically made all Physical Dragons second tier, it didn't matter if they had better speed, pure Dragon typing, more attack, moxie, whatever it is they got or claimed to be better on paper, they never were a complete package. Even the recently included Chomper found it's way back to OU as a lead SR setter or Dragon revenger (of you guessed it, +1 Dragonite). Less important to mention was that it was suspect tested once and was always a top 10 (or top 5) player.
Consequently, when we talk SR and it's importance on the field, the need for spinners and spinblockers, ice moves and priorities, steels, rain, sand, hail, sun, we are never far behind of mentioning Dragonite and why all these decisions matter in team building.
Dragonite.