You Do Need power plug adapter while traveling from Switzerland to Monaco.

Here is Why You Need An Adapter

The outlet and plug type used in Monaco are C, E and F and in Switzerland are C and J. This is how they look like.

Switzerland

In Switzerland, outlets of type C and J are in use.

Type C

Type J

Monaco

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

Type C

Type E

Type F