You Do Need power plug adapter while traveling from Vanuatu to Sudan.

Here is Why You Need An Adapter

The outlet and plug type used in Sudan are C and D and in Vanuatu is I. This is how they look like.

Vanuatu

In Vanuatu, outlets of type I are in use.

Type I

Sudan

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

Type C

Type D