Err what? Mixed set is prolly one of its weaker sets, so idk what you are arguing about. I read your post, but all I see really is you whinging that it fails to kill stall and offence at the same time, which a lot of A tier pokemon struggle to do anyway. NP Thundurus-T utterly cleans right through stall, you don't need to run Mixed for it, or Grass Knot, you just run a set of Thunder / Focus Blast / HP Ice / Nasty Plot and nuke everything. Sure, you can be revenge killed (by offensive teams), but 101 base speed isn't terrible in this metagame, which lets you threaten slower shit such as Landorus-T, Gliscor, Politoed, unboosted Dragonite, and a shitload of other things. You might not find the time to Nasty Plot, but against an offensive team, you don't even need too - a LO Thunder fucking HURTS and can and will blast holes through the team. You won't clean "6-0" but your opponent often has a few pokemon that sit at below 101 base speed, which Thundurus can then exploit by forcing your opponent to either sac / have these pokemon crippled etc (to prevent Thundurus-T getting free attacks off them) or choosing a faster pokmeon to take a hit (which are less likely to take a hit from LO Thundurus-T as well). Agility is a different kettle of fish, trading the usefulness against stall (which is rare, and BW2 introduced new pokemon which rape stall anyway) for exceptional potential vs Offensive teams (you know, the ones that you say will revenge it). With Agility, your opponent pretty much needs to LO stall you, or pick you off with Priority, neither of which are reliable, and its likely Thundurus-T has taken out a pokemon or 2 by the time you take it down. So maybe its not running Agility or NP, heck, maybe its running Double Dance, which lets it pick what boosting move is best for it in a given situation, and then sweeping. Sure, you lose out on coverage, which in turn make you slightly, easier to counter, although depending on its 2nd attack, you can still lose. The set was actually popular recently on suspect for raping that gay Deo-D + 5 sweepers team since Thundurus-T would just punch through with NP + Agility (and be immune to Thunder Wave) but maybe you didn't run into that set so idk. Finally: Thats what you are comparing. Those are the differences and IMO, Thundurus-T can sweep most of the metagame, the main flaws being that it cannot sweep both stall and offensive teams consistently, as well as being SR weak. But then again, its not the only A tier pokemon that cannot do this so ???