Beat any 2 stages in the normal game to unlock 2-player Lammies.
Beat 2-player Lammies to unlock 2-player vs. Lammies.
Beat the 1-player game to play as Parappa.
Beat 1-player Parappa to unlock 2-player Lammy Parappa.
Beat 2-player Lammy Parappa to unlock 2-player vs. Lammy Parappa