Scarf can't be tricked to a Pokemon holding a megastone ...klefki with thunder wave makes this thing sad. So does mega bannette. And pretty much any prankster user with a good support move pool. Also, things that can trick a scarf really stop a sweep, especially if you have mega gengar. As mentioned above, trevanent can take it if it lacks crunch, dusclops, cofagrigous, etc.
Oh, and explosions. I like explosions