Red-August 8
Green/Blue Oak -November 22
Blue/Green- June 1
Yellow-March 3
Gold- July 21
Silver- December 24
Crystal- April 30
Ruby- July 2
Sapphire- September 20
Emerald- May 31
Diamond- December 4th (Sagittarius)
Pearl- Febuary 12th (Aquarius)
And then Platinum, Black, White, Bianca, and Cheron's birthdays have not been revealed yet. Heck, I had to go back to my old 文章 on the Pokemon club to get Diamond and Pearl's birthdays because they are no longer on Bulbapedia anymore.