You Do Need power plug adapter while traveling from Réunion to Seychelles.

Here is Why You Need An Adapter

The outlet and plug type used in Seychelles is G and in Réunion are C and E. This is how they look like.

Réunion

In Réunion, outlets of type C and E are in use.

Type C

Type E

Seychelles

In Seychelles, outlets of type G are in use.

Type G