Shortly before reaching Goldenrod City, I caught a Wobbuffet on the Pokéwalker and added her to my team, just because I had never had the patience to raise one before and wanted to try it. When I got to Whitney, the rest of my team, which was decently leveled, took care of Clefairy. Then I just sent out Wobbuffet who Countered the crap out of Miltank.
I felt like that was a really cheap and unfair thing to do, though, so shortly after the battle, I took Wobbuffet out of my team. :/