You Do Need power plug adapter while traveling from Pakistan to Nepal.

Here is Why You Need An Adapter

The outlet and plug type used in Nepal are C, D and M and in Pakistan are C and D. This is how they look like.

Pakistan

In Pakistan, outlets of type C and D are in use.

Type C

Type D

Nepal

In Nepal, outlets of type C, D and M are in use.

Type C

Type D

Type M