I don't buy this "Reuniclus is good against stall so it must be banned" argument.
If one pokemon can single-handedly take down an entire team, that used to mean the team wasn't good. Maybe stall is dead? "Stall" is not something that has to be a part of the metagame, stop pretending like we require a perfect balance of playstyles to have a competitive metagame. I don't know what fantasy world you're living in, but we're not in a metagame where 1/3 teams are offense, 1/3 are stall and the other 1/3 are balanced. The fact that Reuniclus beats stall teams is irrelevant if stall teams suck in this generation (which they do). Reuniclus also beats mono-Poison teams, what's your point?
And besides, there are still plenty of ways for stall teams to beat Reuniclus. Trick, Taunt, Perish Song, Whirlwind, having something on your team that can actually do damage, Spiritomb, other Calm Minders like Latias and Suicune, etc