You Do Need power plug adapter while traveling from Mozambique to Nauru.

Here is Why You Need An Adapter

The outlet and plug type used in Nauru is I and in Mozambique are C, F and M. This is how they look like.

Mozambique

In Mozambique, outlets of type C, F and M are in use.

Type C

Type F

Type M

Nauru

In Nauru, outlets of type I are in use.

Type I