Rock is a character appearing in the Tag Force series.
In Yu-Gi-Oh! GX Tag Force, Rock is found at the Obelisk Blue dorm, and is grouped with Truly, Celia, Seydina, Dante and Brown as each wield a Deck of one of the six Attributes. Upon acquiring his Deck Recipe, he also gifts the player with an "Earth Chant" card.
In Yu-Gi-Oh! GX Tag Force, Rock plays an EARTH Deck called Ruffian Realm, which also features an array of Spell and Trap Cards that let him trigger the destruction effect of his "Dream Clown".
In later instalments, his Deck focuses more on Rock-type monsters (hence his name).
Tag Force - Ruffian Realm