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

Here is Why You Need An Adapter

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

Nauru

In Nauru, outlets of type I are in use.

Type I

Azores

In Azores, outlets of type B, C and F are in use.

Type B

Type C

Type F