>>47412820The Lati@s being birds thing was from the first teaser poster released. Interestingly, none of the trailers until the ones right before the release of movie 5 actually them (obviously due to the mystery element since the trailers show stuff not in the I lm and are digitally inked) and looking at the production time of each film, we can say that the Lati@s duo were fully conceptualised by at the most Spring-Summer 2001.
Here's a rough timeline of gen 3's pre-release period before the year 2002:
>sometime in 2000: Forming The Pokemon Company, the staff of the games aims to continue the series after seeing the international success it has acquired and decide to make a new game for the upcoming GBA system. This part is purely schizo conjecture but the similarity of Lisa from the 3rd movie's design to May might be something to note>December 2000: Crystal is released. Crystal's battle tower looks similar to the style of houses used in RS, the Japanese code mentioned Ruby and Sapphire>January/February 2001: Takeshi Shudo, writer for the anime, writes his last episode (interviews claim that episodes were already fully done 4 months before release during OS), before leaving, he puts across the motions for AG and decides for Misty to leave when put between a choice for TRio or Misty to leave by the execs. It's not known how involved he was in planning early AG though before he left.>March 2001: Pokemon "Advance" is unveiled at a conference, revealing the Male MC, Azurill, Wailmer, Kecleon and the PokeNav. The Kecleon ep and the Pikaboo short is likely already animated by then. The concept art for Groudon and Torchic is dated from around this time iirc, this might mean that "Latiken" was already split by then looking at the internal data order in the final RS 