Disney alums Demi Lovato and Nick Jonas team up at the State Fair Aug. 31

She overcame addiction and mental illness. He overcame the stigma of being in a boy band. Disney Channel alums Lovato and Jonas have thriving separate pop careers, and now the 23-year-olds are teaming up on tour, even literally sharing the stage. (Remember she dated Joe Jonas, back when she opened for the Jonas Brothers.) She's got plenty of hits, including "Cool for the Summer," and he made a solo splash with "Jealous." Opening is Mike Posner, who made a comeback this year with the popular single "I Took a Pill in Ibiza." (7 p.m. Aug. 31, grandstand, $40-$56.)