Ok. i looks like i was missing their documentation. And after detailed study of their documentation i saw that not just imu or odometry robot localizaton package also supports posewithcoveragestatmped, twist etc other ros topics. Here is what i added in my configuration file so that robot localizaton use the pose calculated by amcl also:
pose0: amcl_pose
pose0_config: [true, true, false,
false, false, false,
false, false, false,
false, false, false,
false, false, false]
pose0_differential: true
pose0_relative: false
pose0_queue_size: 5
pose0_rejection_threshold: 2 # Note the difference in parameter name
pose0_nodelay: false