Yuusha-Ou GaoGaiGar Final

Seires debuted in SRW Alpha Gaiden-SRW J

Every anime related to this cousin Franchise to Transformers, mecha genre.

These are the anime that appear in Super Robot Wars Alpha 3 for PlayStation 2.

These are the anime that appear in Super Robot Wars W for DS.
This is often considered one of, if not the best written Super Robot Wars game, and is a personal favourite of mine.

These are the anime that appear in Supa Robo Gakuen for DS. Yes, it's supposed to be spelled that way.
None of these anime feature any story whatsoever in this game, which saves me a lot of effort.

These are the anime that appear in Super Robot Wars 30 for PS4, Switch, and Steam on PC.

These are the anime that appear in Super Robot Wars X-Omega Second period inclusions Roster For İOS and Android

These are the anime that appear in Super Robot Wars X-Ω, a mobile phone game that is now defunct.
It's being split into multiple parts because there are so many.

Shows that Hironobu Kageyama has sung in, has been credited in, or is plainfully obvious that it's him.

Shows that Masaaki Endoh has sung in, has been credited in, or is plainfully obvious that it's him.

Shows with a song performed by MIO (also known as MIQ).

Every anime I could find that still used cel animation during the early 2000s

Part 4, this time it is specifically for sequels, sequel's sequels, spinoffs and prequels.

Part One: https://myanimelist.net/stacks/30488
Part Two: https://myanimelist.net/stacks/30490
Part Three: https://myanimelist.net/stacks/30498

Note: Moderators had taken down the stacks before, since it was not wholly information based. I will post this as a note as to why such series are essential in order to defend them all as a blanket statement.

Most of the series featured have some sort of significance in terms of first best or darkest for their era which can be categorized by decennium or part of a decennium (early, middle, late). These are mixed around in order in order to give those who subscribed to list a challenge. While I could give an individual breakdown, I think some research is better left up to those who have subscribed to the stacks, since this allows for additional cultural insight into what was popular in Japan at the time, which is sometimes disconnected from the United States, as well as the rest of North America and Europe in many ways. For example, the Crayon Shin-Chan that aired in the United States and Canada is different to the one that aired in Europe, is different to the one that aired in Japan. By recommending to seek out Japanese versions of series, it grows understanding. I am not the first one to have thought of this. In the United States, there used to be a channel called ImaginAsian TV which had the same purpose of informing people about Japanese popular culture through anime. The San Francisco and San Diego PBS stations did the same thing and NHK World Japan carries this on through series like Little Charo and previously Maiko-san Chi no Makanai-san.

I think it is agreed upon that retro is a niche, but with handicaps on subject matter like availability.

All the brave shows and other related Brave media in release order.
Bang Brave Bang Bravern isn't technically part of the Brave series it's a Super Robot spiritual successor. So who knows maybe well get more Braves in the near future
Keeping this up to date if things change or something new comes out!!

Anime featuring mainly traditionally animated, hand drawn robots made between the year 2000 and 2009. As CGI started being used in anime in this period, some mecha series started shifting towards CGI robots, I think this list would be really helpful.

Note: The Big O Season 2 doesn't have its own entry on MAL, so it's being represented here by its first season, which doesn't meet the criteria, but I got no choice.