Trainer Yusuf

I should be making actual blogs instead of this stuff, but this relevant for what's been currently going up in the forums. This will be talking about of stuff for Advanced Generation and on because a)due to most of information before than being spread through physical media it makes them hard to track from Internet and b)Bulbapedia has extensive documentation for the pre-release information, at least for Gen II titles, and I am pretty sure you can find about Blue's release as it was a special edition release.

Anyways, without further ado, let's start:

Ruby/Sapphire:
First information about the Pokémon: First batch of Gen III Pokémon were revealed in early March 2001. You can see the news here.
First information about the games: First screenshots came out in March 2002

Firered and Leafgreen:
First information: September 2003 Very first rumors came out in 5th.

Emerald:
First information: June 2004, magazine cover. Actual info came out in the next month's Corocoro.

Diamond/Pearl:
First information about the Pokémon: Munchlax was revealed in May 2004.
First information about the games: Names came out in October 2004. First screenshots came out in May 2006

Platinum:
First information about the Pokémon: Origin Forme Giratina was revealed in February 2008.
First information about the games: Came out in May 2008.

Heartgold/Soulsilver:
First Information: May 2009

Black/White:
First information about the Pokémon: February 2010
First information about the games: April 2010

Black 2/White 2:
First information: February 2012