You Do Need power plug adapter while traveling from Pakistan to Guinea-Bissau.

Here is Why You Need An Adapter

The outlet and plug type used in Guinea-Bissau is C 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

Guinea-Bissau

In Guinea-Bissau, outlets of type C are in use.

Type C