Because of Reuniclus's horrible base Speed, anything with Encore can ruin the CMer, especially Wobbuffet, who's actually faster despite having 33 base Speed. Magic Guard doesn't save it from being Slept either, so a sleeper can come in on a revenge and ruin it. Smeargle in particular can come in and Spore Rankurusu, and then set up something to pass to his teammate. Although I haven't used it before, Shubargo seems like a potentially good counter, since it resists Psychic, can afford to dump all its EVs into HP to weaken Focus Blast, and can destroy Reuniclus with Megahorn. He can even beat the Trick Room version because his base Speed is lower than Reuniclus's. As people have mentioned, Trick is a great counter for Reuniclus, because then it can't Recover its health and is locked into one move. Spiritomb of course is a great counter, who also seems to counter a lot of things in the metagame (yet people refuse to use it because "it's Spiritomb", which is absolutely retarded).
Specially Defensive Drapion, which was a pretty good set in Gen 4, can make a return to counter Reuniclus, due to immunity to Psycho Shock, super effective Crunch, and ability to take Reuniclus's attacks. Scizor of course is faster and hits with super-effective Bug moves.
Reuniclus seriously isn't that hard to play around; it seems extremely deadly on paper, but in practice, while it is admittedly a good pokemon, it's
nowhere near broken. Also, I'm seeing some contradictions between some of the pro-ban Reuniclus people, which is making Reuniclus look a lot less counterable than it actually is. One minute they're saying that Reuniclus has 252 HP/252 Def Bold and it can take Crunches nice and easily. The next minute they're saying it also happens to have max SpA when they're basically implying that this guy OHKOs the metagame (yes I know no one actually said that, but it's definitely being implied when people basically say there's no counters and that nothing can switch in safely). Sorry, but you people are going to have to make up your mind. Last time I checked, the max amount of EVs a pokemon can have is 510, and 252+252+252 does not equal 510. Also, Reuniclus can't have Psycho Shock/Calm Mind/Recover/Shadow Ball/Focus Blast/Trick Room all on the same set.
Another thing I don't understand is that people were hating on Kyurem for having to rely on Focus Blast for coverage, but they seem to be perfectly fine with Reuniclus using it for coverage, despite the fact that most of the things Reuniclus is using it on will kill it if Focus Blast misses. Ie. If Focus Blast misses against Scizor, Reuniclus is either dead or on life support. There's also Tyranitar, who does the same thing. Sazandora can have the same deal as well. I don't know where this double standard came from.
One last thing is that it's not so easy for Reuniclus to just Recover off damage. 30 base Speed doesn't exactly allow for fast recovery, so if he took a big hit in the previous turn while he was trying to set up or attack, it's not likely that he can take another one since he'll be too slow to recover the damage off before the opposing pokemon attacks.
Also, I find it absurd that people are saying that Stall is unviable with Reuniclus around. Obviously people are still using Stall for a reason; if it was unviable, no one would use it.
As long as Team Preview exists, Stall will always be viable IMO. Although I don't play Stall very much, those Physically Defensive Gyarados on Stall teams seem like they'd give Reuniclus a run for his money, and last Gen, a lot of Stall teams carried ScarfTar on the team just as a good stopper to Trick users; it doesn't seem any less viable now. Even though Crunch probably won't OHKO, it'll still do a lot of damage. Reuniclus will definitely not enjoy physically defensive Gliscor either, since Acrobat will definitely have Reuniclus recovering more than it would like to. Also, Reuniclus might hurt pure stall, but stall teams that don't carry completely offenseless pokemon will stand a chance.
Those who complain he makes stall unviable should also ban Shinpora,who can use Cosmic Power to make itself even bulkier than Reuniclus and has a trolled speed of 97(Still enough to out speed a few things) and fire off strong Assist Powers.
Agreed. Shinpora even has Roost, and because he's pretty fast, he might actually be able to get his recovery before the opponent lands their hit. And because of Cosmic Power, he can even stomach Crunches after a few and just Recover off the damage due to Cosmic Power raising both defenses. Reuniclus can stomach certain Crunches, but if he accidentally gets hit by one due to a misprediction and didn't use Recover that turn, he probably won't live through the next turn.