@ CD: I went on a bit of a RNG rampage recently, getting Cobalion, Terrakion, Virizion, Tornadus and Landorus. I was mainly going for Tornadus but got everything else on the way! I may never use them but who knows?
Yeah I have used Gyarados a lot and it does suck as an attacker, mainly because Waterfall isn't really that powerful, as well as the fact that its movepool sucks. It's basically Waterfall/Aqua Tail, Return/Double-Edge (no supereffective coverage but excellent neutral coverage), Stone Edge (but no Rock Slide for some dumb reason; Stone Edge is awful in subway anyway), Ice Fang (weak and not 100% accurate; it's only good for Flying Dragons/Gliscor/Landorus), Earthquake (redundant coverage with Waterfall)...
The most success I had with it was my Trick Room team, funnily enough, because I was able to EV it in attack and defence without worrying so much about it being too slow. I always get suckered into using it due to its typing and Intimidate and it always underwhelms me. But I see your point, it doesn't really bring anything particularly essential to my team.
I do have a Thick Fat Mamoswine but it has trash IVs and nature. Hopefully Swinub be released as a female in the upcoming GL update. Actually I did cast my mind to Azumarill for a moment but yeah that speed. I might try it out anyway though because Adamant + 252 speed has 204 speed in Tailwind which is acceptable I guess, or maybe Feraligatr (faster though not as powerful) or something like that, I don't know yet.
But yes you did talk me out of Gyarados so thank you! Now I don't have to bother with 3rd gen RNG to get Double-Edge :p
@ BowlArt64: Yes I did consider Metagross, but then my team would be even more similar to Peterko's! I'll see.