Kalos doesn't have a flag, does it?
I don't believe so. In fact, I don't recall any regions having their own flags.
I'd imagine Joey would've probably labelled Pokémon under Nintendo Land, Game Freak Land or Pokémon Land.
You could always use this though:
A: I was just askin' if there was.
B: Yeah he sorta did call it one of those (judging by some unused ports for Pikachu/Pichu, Snorlax, Gardevoir and Gallade, but...I think countries named "X Land" or something like that seem overdone.
C: Okay, I'll consider using that.
The colours of that flag remind me of France. So... Viva la France! XD
yeah, blue red and white remember me francia