Clarification regarding Masuda Method

[Dread]

Let's say for an instance I have a US cartridge. Will the Pokemon I caught in it partnered with an ITA Ditto activate the Masuda Method for shiny breeding?
I have read different ideas about it such as JPN Dittos being the best bet, or as long as you can see a black tag above the summary of a Pokemon it would work.

[GameGeeks]

From what I've gathered it should. All that seems to matter is a different region. Italy is certainly a different region then the US. My guess is that as long as there's a tag it should work. Might get iffy if you live in the UK. And Canada and Mexico might be considered the same region as the US.

[Excalibur0126]

From what I can tell, It works if the two pokemon have different region tags. Like Mexico and Italy, or Japan and Germany.

[Dread]

I guess it's okay then. Thanks for the answers!