As a competitive Pokemon player, let me just say that Klefki is not only incredibly good, but incredibly annoying. It mainly has to do with the fact that it has the ability Prankster, which makes all non-attacking moves go first, meaning it can fully invest in its bulk while still outspending the opponent. Couple that with an incredible support move pool and a great defensive typing, and you have a Pokemon that has resulted in more hair loss than balding itself.

Prankster's a hell of an ability.