I am floored by the lack of Nidoking after 7 pages. Also, I like using Mew like a Ditto for the increased health and overall versatility to combat offensive, defensive, and Megas alike.
Nidoking @ Life Orb / Choice Scarf
Ability: Sheer Force
EVs: 252 Spd / 4 SpD / 252 SAtk
Timid/Modest Nature
- Earth Power
- Fire Blast
- Ice Beam / Thunderbolt / Surf
- Sludge Wave / Focus Blast / Shadow Ball
The slashes are there just to show how versatile this guy actually is; you can run almost any special attacking move you want to suit your team's needs. With that lovely Sheer Force ability and Life Orb, he is always at more than +1, so he can always hit like a truck. Or, if you need more speed, give him a Choice Scarf to put that base 85 speed to good use. I personally get the best of both worlds on my team with Life Orb and Tailwind support, but to each his own, you know.
Nidoking @ Life Orb / Choice Scarf / Choice Band
Ability: Sheer Force
EVs: 252 Spd / 252 Atk / 4 Def
Jolly / Adamant Nature
- Earthquake
- Poison Jab
- Megahorn / Stone Edge / Sucker Punch
- ThunderPunch / Fire Punch / Ice Punch
With its newly buffed Attack stat and the elemental punches from 5th Gen, Nidoking can go physical to defeat its typical checks and counters and still function to a similar effect. Earthquake, Megahorn, and Sucker Punch suffer since they have no secondary effect, but his Attack stat and STAB on Earthquake make up for it.
Now for my Mew set:
Mew @ Choice Scarf / Leftovers
Ability: Synchronize
EVs: 252 HP / 252 Spe / 4 Atk
Jolly Nature
- Transform
- Hypnosis
- Taunt
- Trick / Explosion
Self-explanatory set: Transform into an opposing Pokemon of your choice, preferably a Mega or a bulky attacker, after crippling with your choice of Taunt, Hypnosis, or Trick (if you carry it). If you don't find anything worth copying and you need a threat eliminated fast, Explosion can serve as a fail-safe to quickly destroy a threat.