When it comes to coaches on The Voice, it's become sort of a revolving door of talent. Unlike most talent competition shows that attempted to retain their judging panel season after season, The Voice has owned the fact that they could literally get anyone to sit in the turning chairs for a season or two. When it all started, the quartet of coaches represented the various genres of music. Adam Levine was pop-rock. Blake Shelton was country music. Christina Aguilera was pop. CeeLo Green was R&B.