You Do Need power plug adapter while traveling from Aruba to Tonga.

Here is Why You Need An Adapter

The outlet and plug type used in Tonga is I and in Aruba are A, B and F. This is how they look like.

Aruba

In Aruba, outlets of type A, B and F are in use.

Type A

Type B

Type F

Tonga

In Tonga, outlets of type I are in use.

Type I