Comment on statement: in pure rotational motion, the instantaneous velocity of all the particles is same. Explain your answer.

The statement is wrong.
Magnitude of the instantaneous velocity of an arbitrary particle = rω.
Direction is along the tangent to the circular path followed by the particle.
The particles are at different distances from the axis of rotation and have different magnitude of velocity and the particles which are at the same distance have different direction of velocity.
Therefore, the instantaneous velocity of different particles is different either in magnitude or direction or both.