The Masuda method involves breeding two Pokémon created in games of different countries.
You can use any foreign Pokemon for it to work. They can both be from a different country than yours as long as they aren't from the same one.
If both Pokémon are foreign to the cartridge but are both from the same country, then the Masuda method will not take effect.
Source: knowledge and Bulbapedia
Hope I helped. :]