Wobbuffet's ability, shadow tag prevents your opponent from switching Pokemon. Although it can't attack, it can counter attack. It can also learn encore, which makes your opponents' Pokemon use the same move for 2-6 turns. With this in mind, you can force your opponent's Pokemon to attack a few times, and counter its attacks. Wobbuffet has a lot of HP, but poor defenses, but it can manage to take out 1-2 Pokemon. Maybe even more. Another thing it can do, is encore a stat boosting move (Sword's Dance) and switch to another Pokemon and do some damage. Using Encore on a status move and switching to a Pokemon with the guts ability is also nice. Anyway, I might as well sign up for this.