It'll be interesting to try this - downloading now.
Since JPN/USA game saves are interchangeable, I'll try my Pearl save first, catch a Korean Pokemon, then use my USA game again. I'll also examine Korean save under Pokesav.
Wonder what will happen.
EDIT: The save does not seem to be compatible. Got pwned by Rowan (new game started)
EDIT: This is getting creepy. After saving over my file in the Korean game, I go into Pokesav to look at it and my old Pokemon are still there!!!
Upon restarting the Korean game, I find that the game had indeed saved successfully. But Pokesav could still read the old data. Hmm...
EDIT: NVM, another save after Piplup obtained wiped the data. Pokesav is getting me a proper reading. Can read Piplup but not display Korean characters.
The Piplup's country setting in Pokesav is (none) but might be because the KOR region is not set in Pokesav.
EDIT: The wireless capability is hopeless incompatible with the USA version.
I'm too lazy to try with PBR... but there's a safe bet it will not work.