In How to batch edit Z values and set them all to zero, @AaronManuel2 said:
I have a line feature class with about 80k rows...I'd like to change the z-value for all vertices in this feature to 0...I am aware of the Adjust 3D Z tool but the problem is this tool only lets you set a relative value instead of an absolute value.
Could a GP tool be added that would allow us to batch-apply an absolute Z or M value to multiple features?