Although I see why Wobbuffet would be considered Uber by some, I have him allowed in this tournament. There are several ways to defeat a Wobbuffet, with my personal favourite being striking him with Special Dark attacks from a Dark-Type. =P
Encore can be pretty annoying on this guy, though. >_>
But it's not taking him down that's scary - it's his trait which makes him truly frightening. So to take him down with a Dark Pokemon, you have to be lucky and either catch him on the switch-in, or predict and switch in with him. Don't forget, his trait traps you in battle, so there's no way to actually counter this guy unless you're extremely good at prediction; or the person using him is just stupid. XD
Also, why is Wobbuffet uber again? I mean I understand the whole mirror coat/counter/destiny bond argument, but his base stats are sub par at best.
Wobbuffet is uber mainly because of his trait Shadow Tag, I think it is. It traps you, and you're either Encored so your opponent can set up a sweeper, or your futile attempts to KO it are shattered when he fires back with Mirror Coat or Counter, and OHKOs you, because with his insane HP, very few things will knock this beast out in one move. And finally, Destiny Bond for a final killing, because Wobbuffet never dies alone; essentially, Wobbuffet is a guaranteed OHKO on
at least two Pokemon. And if you have Wish support, Wobbuffet can take out an entire team.
Oh, also, as someone above mentioned, it's said that Wobbuffet vs. Wobbuffet is an automatic stalemate; neither can switch out, and neither can attack each other. I'm not sure if it's ever happened, but I do know that I never
want to see it happen.
In my opinion, Wobbuffet is the scariest of all ubers.