It's a showdown of harmony when Grammy winners Pentatonix lyrically battle '90s pioneers Bell Biv Devoe, and we find out which host has the hottest bars between Top Chef's Padma Lakshmi and American Idol's Randy Jackson.

Actor David Arquette puts his rap skills to the test against Brian Tyree Henry ("Atlanta"); Jesse Tyler Ferguson ("Modern Family") raps for the first time in a battle against Chrissy Metz ("This Is Us").

Wayne Brady, known for being quick on his feet, takes on country singer Jake Owen; Kenny G and Richard Marx engage in a rap battle.

It's a "Big Bang Theory" rap battle as co-stars Mayim Bialik & Kunal Nayyar go rhyme for rhyme, while High School Musical princess Ashley Tisdale challenges Nick Lachey to a battle you never knew you wanted.

Vanessa Hudgens vs. Michael Bennett & James Corden vs. Nicole Richie.

TV host and Pussycat Doll Nicole Scherzinger spits hot fire against "Get Out" funnyman Lil Rel Howery; an unprecedented 5-on-1 takes place when singer Charlie Puth takes on every single member of the Backstreet Boys.