You Do Need power plug adapter while traveling from Mongolia to Botswana.

Here is Why You Need An Adapter

The outlet and plug type used in Botswana are D and G and in Mongolia are C and E. This is how they look like.

Mongolia

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

Type C

Type E

Botswana

In Botswana, outlets of type D and G are in use.

Type D

Type G