A subber + DT? There is a pokemon that resists every single 2 attack combo in the game. (Ground/Dragon == Skarm. Ground/Ice == Bronzong. Fire / Dragon == Heatran. Bolt/Beam == Magnezone / Lanturn. Water/Normal == Empoleon. etc. etc.) No matter what the 2 attacks are, I can guarentee a resist.
The only "exception" is HP Fight or Aura Sphere / Shadow Ball... but Blissey walls the most powerful users of this combo. Lucario, Togekiss and Mismagius require Calm Mind, Nasty Plot, or Choice Specs to break Blissey, which means you either lose DT, or you lose Subsitute. Mixcario with Sub/DT is walled by Bulky-Gyara... and has better sets than Close Combat / Shadow Ball anyway.
So... please tell me a specific pokemon that gets both Subsitute and DT that isn't totally walled. While I'm certain DT sets would exist, they certainly will not exist on an offensive sub+DT varient. Maybe there will be an offensive set that actually manages to scare away its counters (only to be countered by X pokemon who resists your 2-attack combo...)... but it certainly won't exist on everything.
Obi: I'll respond later. You bring up a few good points and I'd rather be more careful and redo my calculations a few more times. I generally focus on 1, 2, or 3 stat ups because frankly... if you get 6 free turns onto a pokeon you deserve to lose. The lower number stat-ups are more typical in my experience.