5. Hitmonchan would be the first Rapid Spin user that actually resists Stealth Rock in NU. Does it directly outclass Torkoal, Armaldo, and Wartortle to the point that they should no longer be used for those roles? Do any of those still have advantages over Hitmonchan? Will other, non-Rapid Spin sets receive usage? What would be the best of these? Which Pokemon are the best counters for Hitmonchan? What teammates would appreciate Hitmontop's support the most (and I don't mean just list 4x SR weaknesses, think about it a bit!)
Hitmonchan's reputation in RU is poor. Against the Ghost-types in RU, Hitmonchan was dependent on Foresight to hit them hard and otherwise spin. That said, Hitmonchan dropping to NU would theoretically be more of a relief. Resisting Stealth Rock and Rapid Spinning it? Who'd have thought?
Of course, to make sure Hitmonchan is even remotely close to a viable Rapid Spinner, calcs are in order to see how it will compete with the Ghost-types of the NU tier (of which there are surprisingly few). Hitmonchan's main set is the RU Rapid Spin set, so that set is what will be opposing the many sets of the surprisingly few Ghost-types in the tier:
Hitomonchan v. Haunter - almost always a 2HKO (with a very low chance of OHKO after Stealth Rock)
Hitmonchan v. Misdreavus - if Foresight Drain Punches were involved, these would be 3HKO's; however, bar the Nasty Plot set (which is still only 3HKO'd by Ice Punch), Misdreavus can comfortably take Hitmonchan's Ice Punches (5HKO's, 4HKO's after SR)
Hitmonchan v. Golurk - 2HKO's across the board with Ice Punch, Stealth Rock does not help change Ice Punch to be an OHKO at all
Hitmonchan v. Drifblim - 2HKO's, some sets can be definitely OHKO'd after Stealth Rock (but not all of them!)
Hitmonchan v. Lampent - Ice Punch sucks against Lampent, so assuming Foresight was used on the switch - Drain Punch will give a reasonable chance of 2HKOing Lampent. With Stealth Rock, the 2HKO is guaranteed. No OHKO's here either.
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.