Originally Posted by Fat /B/utterfree
Comparatively, Armaldo's offensive Rapid Spin set can definitely OHKO Haunter, Lampent, and Drifblim without boosts/Foresight (but does in fact have a harder time with Golurk than Hitmonchan at any rate, only netting 4HKO's unboosted). Torkoal and Wartortle, on the other hand, would be replaced by Hitmonchan almost outright in the case of the former (Smashkoal can go toe to toe with the Ghost-types almost as well as Hitmonchan, if not better in some cases, such as under Gravity with Earth Power), and definitely replaced in the case of the latter.
Other sets might see usage. However, without sufficient boosts from the Bulk Up set, the circumstances are almost exactly the same with some of the same moves (although Life Orb hits slightly harder at any rate - not enough to make an overall difference, however).
Super-effective hits from Flying and Psychic types easily dismantle Hitmonchan, even with its base 110 Special Defense. Its base physical Defense is 79, and its base HP is 50. This means it is frailer than the other Rapid Spinners overall. Dark-types and Steel-types alike each serve to make Hitmonchan's job of Rapid Spinning much easier, the latter even resisting Stealth Rock on the whole even if Hitmonchan fails at Rapid Spinning. The Dark-types (such as Skuntank!) will also provide elimination of the Ghost-type obstacles (especially since some of those Ghost-types are faster than Hitmonchan!).
All in all, Hitmonchan would still be a decent addition to NU if it (hopefully) dropped. Spinblockers are still going to be serious business, though.
I'm not entirely sure that Wartortle would be replaced by Hitmonchan entirely. Wartortle is still the bulkiest spinner in NU, and the potential to burn an incoming switchin is pretty immense. Hitmonchan's typing also holds it back at the same time that it is a benefit, with weaknesses to Flying and Psychic quite crippling in the current NU metagame.
What really holds Hitmonchan back in my opinion is its speed tier - 76 sits just below the magic 80 of NU. This means things like Gardevoir can easily switch in and threaten the OHKO with Psychic (both offensive and defensive sets can comfortably take a hit). Even Garbodor threatens an OHKO with Gunk Shot while Hitmonchan does jack to it, while Wartortle can at least pray for a burn. The fact that Hitmonchan is very dependent on prediction also hampers it - AcroBlimp can be beaten soundly with Ice Punch with SR, but choosing the wrong move immediately threatens it with death. Wartortle can't hit a sack of beans, but at the very least Scald is a fairly reliable move in general, and Seismic Toss or Toxic are always options for it, while Hitmonchan would have to give up Iron Fist for Seismic Toss (not that it should, since Drain Punch outclasses it in almost every way).
Hitmonchan's big prize is its capability to hit hard, yet that also exposes its immense frailty. I think a 252HP/40Atk spread might be more viable for it, as it allows it to take a hit or two while still threatening enough offense to KO crucial threats.
I think Hitmonchan would certainly carve out its unique niche - it'd be the fastest spinner, and can actually threaten Pokemon like Cincinno from switching in - but I doubt it'd replace the bulkier spinners.