You Do Need power plug adapter while traveling from Pitcairn Islands to Zambia.

Here is Why You Need An Adapter

The outlet and plug type used in Zambia are C, D and G and in Pitcairn Islands is I. This is how they look like.

Pitcairn Islands

In Pitcairn Islands, outlets of type I are in use.

Type I

Zambia

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

Type C

Type D

Type G