Masuda Method - What counts as a region?

Question

So the Masuda Method of breeding is simple, breed two Pokemon obtained from different regions in the world and your odds of the egg being a shiny increase.

My question however is, being from the UK, will breeding one of my Pokemon with one from an American friend work? I know this may sound silly, since the UK and USA are clearly different regions of the world, however all my Japanese Pokemon have a little black box on their information screens to clearly show that they are from another region with the letters JPN on it. In some videos, I've also seen some Pokemon with a black box that shows the word FRE, which I'm assuming means it is a French Pokemon.

Sadly, no such thing for any of my friends USA Pokemon. Why is this? My American friend did trade her Poke to another one of my friends in the UK, before that UK friend traded it to me. Did this change it from a USA Pokemon to a UK one or something?

Answer 1

The Pokemon must be in a language other than your current system language in order for it to count. This means that Trading UK<-->US or other English-speaking countries won't work.

As a general rule of thumb, if a Pokemon has the 'region' tag ([JAP],[FRE],[GER],[ITA],[ENG] etc), it will count for the Masuda method.

Read more about the Masuda Method on Bulbapedia

References:

• Bulbapedia Talk Page
• Pokemon DB
• 3DS Forums

Answer 2

but bulbapedia also states:

"The most common way to arrange such a pairing is to use one foreign Pokémon and one from the game in which the breeding occurs, although the method will work in any game provided at least one of the Pokémon in the pair is from a country different to the country of the game cartridge."

this sounds like it just has to come from a foreign cartridge, and that those language markers are just for show. I've also been told that selecting a different language for your cartridge will change the "language" of the pokemon. and that would defeat the purpose of the method in the first place.