“Sherman’s Showcase” stars and creators Diallo Riddle and Bashir Salahuddin are elevating their comedic gifts for season 2. With guest appearances by singer John Legend, rapper Phonte Coleman of the hip-hop group Little Brother, and others this season will usher in those needed laughs. “Sherman’s Showcase” airs Fridays at 10 p.m. EST on AMC and 11 p.m. EST premiere on IFC.