You Do Need power plug adapter while traveling from Mexico to Cambodia.

Here is Why You Need An Adapter

The outlet and plug type used in Cambodia are A, C and G and in Mexico are A and B. This is how they look like.

Mexico

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

Type A

Type B

Cambodia

In Cambodia, outlets of type A, C and G are in use.

Type A

Type C

Type G