Throh is honestly just part of Gamefreak's plan to copy every pokemon from the previous generation. It's a Hariyama. That's it.
And keeping with Gamefreak's trend, like all other pokemon that were remakes of some other (Galvantula to Ariados, Ursuring to Beartic... I could go on), Throh's stats are completely inferior to Hariyama's. So anything Throh can do, Hariyama can do better.
I guess he does have pretty nice stats on paper, but his movepool is basically just a big gimmick. He has Dragon Tail and Frost Breath, but as Fighting type moves. Circle Throw he could pull of, but having an attack that only does Crits is kinda dumb; there are lots of pokemon that have abilities that deny crits or increases their Attack when there is a crit.
Besides that, he really is just another Fighting type. He has the punches and Edgequake, and a bunch of Fighting type moves and Bulk Up. So does Conkledurr. But Throh has to use Superpower in his sets, making him stronger! Almost every other Fighting type has Superpower or Close Combat (which is better) and superior stats.
Honestly, Throh doesn't have anything that really makes him stand out. There are so many other Fighting types (and pokemon in general) that do his job better. He's even outclassed in NU.
Point is, Throh is amazing for in-game, but competitively, he's a no-go.
The main problem with this argument is the fact that by most tiering systems, Hariyama is the equivalent of RU while Throh is NU, and thus are hard to compare/contrast because they don't have to worry about the same metagame. Throh is actually a really good Pokemon in NU, its only downfall really is its speed and lack of reliable recovery other than Rest. As mentioned earlier, Throh has the advantage of having Circle Throw and incredible bulk (which sets him apart from other Fighting types), Circle Throw allowing Throh to phaze out either Pokemon setting up with Throh (as Throh generally runs a Bulk Up set), or adds team support to a team with hazards. Also, you got Circle Throw mixed up with Storm Throw (CT phazes, ST crits), so despite it being outclassed by other Fightings, most if not all of those Fightings are in a different tier. The only Fightings that may be outclassing Throh in other regards are Emboar, who gets powerful Fire STAB and good coverage, or Sawk who is used as either a wall breaker or revenge killer. Throh can also be used to take annoying statuses as Guts then boosts his Attack and makes Circle Throw even more abusable.
Essentially (this is for the tl;dr people), Throh has it's own niche in NU, and is likely the best phazer in the tier, making it useful to teams that have trouble with set up Pokemon (as Throh has enough bulk to withstand a +1 hit from quite a few pokemon and subsequently phaze them out), or make quick hash of an opponent's team when you have hazards set up.