1987 Rocksteady is the representation of Rocksteady from the 1987 TV series. He appears in Wanted: Bebop and Rocksteady, together with 1987 Bebop. There, they are both left behind by 1987 Krang and 1987 Shredder on the 1987 Earth.
By the end, they are encouraged by the 1987 Turtles to choose their own lives instead of following orders.