I love how this entire discussion has degenerated into pointless arguing, when no one - I'm speaking to you, masterful - has still answered the main question of the thread.
 
Why Reuniclus should be a suspect only because it single-handedly halts the common variants of full stall? Why full stall even deserves to exist to the point we need to ban everything which makes it unviable?
 
Every Pokémon we banned so far was a serious problem for all the playstyles, not only one of them. Darkrai was not banned because it was a problem only for offense, or stall, or balance, or whatever. He was banned because all playstyles needed to rely on extreme measures to control him and, even then, he could sweep without much effort (the fact that Iconic's team, one of the most successful in the "BW Darkrai era", relied on Lum Berry Scizor to deal with him is testament enough of this). Masterful's example of an hypotetic OU Rayquaza forcing everyone (note: not only stall, or offense. Everyone) to carry, say, CB Mamoswine to check it is another good case.
 
In Reuniclus' case, however, the situation is completely different. I never saw any good offensive team (aside from poorly made HO teams which roll over to any Trick Room Pokémon or Crocune) having problems with Reuniclus, unless Reuniclus' user managed to eliminate the several checks/counters on the opponent's team (Tricksters, powerful attackers, Scizor etc). Even Semi-stall has little problem dealing with him. The only style which actually suffers is Full Stall. Ok, good, and so? Did we ban Tyranitar in 4th gen because it made, say, Sun or Hail teams unusable? No. Why full stall is somehow special? It isn't, and if it can't keep up with the metagame, it should simply disappear (or maybe show up in other tiers).
 
If anyone can make a good case for why full stall deserves a better treatment compared to Hail stall or all the other neglected playstyle, they're welcome. Until then, please don't use the "Reuniclus destroys full stall" argument as a reason alone to ban him. Thank you.