I'm trying to make a turtlebot like robot using only the RPLidar. Hence I donot have a good source for odometry. I'm getting the Pose2D using laser_scan_matcher, and can use the values and represent it in nav_msgs/Odometry.

I've also found a way to use these pose2D values with /scan headers to roughly calculate velocities.

But I want to know is it mandatory to have Twist information for move_base to work? Or does move_base only require Pose from the odometry messages?

move_base doesn't require any odometry as per the diagram in the document (couldn't get the image link to work). However, it is the local_planner that requires information about your motion (specifically velocity so that it can extrapolate a dynamic path).

Does move_base require Twist from Odometry? - ROS Answers: Open Source Q&A Forum