Importing characters
To import custom soldiers from other sources, copy the provided bin file to the Importable character pool folder—the same place your character pools export to—and boot up XCOM 2. Head to the Character Pool from the main menu again, but this time, click on Import Character. Find the name of the bin file you’d like to import from and give it a click.

CREDIT: http://www.pcgamer.com/how-to-share-and-import-custom-xcom-2-soldiers/