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

Here is Why You Need An Adapter

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

Seychelles

In Seychelles, outlets of type G are in use.

Type G

Slovenia

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

Type C

Type F