Question

How do you get a Pokemon from a different country to use the Masuda Method?

Answer 1

In games where internet communication is still supported, the easiest method is to perform a bunch of Surprise Trades, especially if you do so when more foreign players will be online (e.g. late at night). You can also use the GTS or Link Trades if you're searching for a particular Pokemon.

If you can't trade online, there are three games that trade the player a foreign Pokemon in-game. These are:

1. Diamond/Pearl/Platinum
2. HeartGold/SoulSilver
3. Brilliant Diamond/Shining Pearl

In the Sinnoh-based games, the Meister on Route 226 will trade his Magikarp for your Finneon. In HGSS, Lt. Surge will trade his Pikachu for your own. Both of these Pokemon will work with the Masuda Method.

Additionally, in English releases of Diamond and Pearl, there are three Pokemon that are functionally Japanese and will activate the Masuda Method: Abra, Chatot, and Haunter.

1. Abra: Trade Machop in Oreburgh City
2. Chatot: Trade Buizel in the Eterna Condominiums
3. Haunter: Trade Medicham in Snowpoint City

In-game trade (Bulbapedia)

Answer 2

The easiest way to do this is simply to Trade on the GTS. Since it's wifi, you can get trades from all over the world.