Well in America.. we call him Blue.. Stop saying its "Green" because everywhere in America, his name is Blue or Gary.. Green was the chick. When you go make a comment about someone's art, remember just because its "Green" in the Japanese version doesn't mean its automatically correct. Even bulbapedia says its Blue.. Stop arguing about it, because in the end who really cares? If you want to make a comment on his work, just say "Rival" instead of "It's Green you know that right?" Disrespectful.
In the American translations, they call Green as Blue, and Blue as Green. I think it's cuz in Japan they had released the first generation games Red, Green, and then Blue, (and of course Yellow) while in America they only released Red and Blue, then Yellow.
Blue in english version, because original "red" and "green" games became "Red" and "Blue" when they came to America. Yet they had FireRed and LeafGreen. :/ Weird and a tad stupid huh. I prefer calling him Green too, I think of the pokemon adventures manga where Blue is a different girl