You Do Need power plug adapter while traveling from Falkland Islands to Marshall Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Marshall Islands are A and B and in Falkland Islands is G. This is how they look like.

Falkland Islands

In Falkland Islands, outlets of type G are in use.

Type G

Marshall Islands

In Marshall Islands, outlets of type A and B are in use.

Type A

Type B