The Monsters Empire website (the relocated version of the link found at CT) is an incredible resource. The pictures are a great way to see what stuff is out there, but the seller doesn't often picture reissues (and their superior color schemes) all that often, but does when an improved mold is released.
What's even more useful is the text-based checklist. It took some work to correlate the listings with kaiju since I couldn't go by Google translations alone to make sense of it, but for the past couple of years, I've maintained a checklist of every UMS figure out there. It's probably not complete, but it has to be quite elusive, or too new, for me to miss it. I don't think it fits in a single post anymore.
I've also archived the official Bandai toy images of the most recent figure releases, from Nexus, Max, Mebius, and the 2007-8 series, plus most of the newer EX figures. I even have a website I've devoted to start sharing this information, but I'm way behind and it's really barebones, not to mention a mere freebie thing: http://www.freewebs.com/pedoleon/ Haven't included the list yet either.
I also didn't mention it in my previous post, but in the beginning, Bandai manufactured all of its Ultraman figures in Japan. The originals are made of a much harder vinyl than current figures and usually have sparse or inaccurate detailing. Of course, Bandai eventually began making them wherever it was cheaper, ultimately leading to China. Also over time, the figures were made of a softer vinyl, which you've already seen. Since I don't own many older figures, I don't know how much of a difference it's been since '83.
Still, newer series also mean improvements in the figures. Baltan's current form is a far cry from the original mold, in sculpt and colors. But for whatever reason, Bandai continues to use the same mold, only softer and slightly smaller in size, for other kaiju. Zetton and Mephiras Seijin are more or less identical molds to their 1983 counterparts!
Another change over time started with the 2000 UMS in August 2001, where Bandai allowed the line to become much more malleable. Certain figures were "retired" and replaced with other sculpts. Some, like Gomess, were all-new molds originally released as EX figures (or more precisely, numbered as "2000AD") that were branded with an older kaiju's number. Others were shuffled out in favor of other older figure molds that were being used again. The last big change was in 2004, when Bandai cut the series size down from its original 70 to 60. That's why I only estimated the series number - by my count, the 2000 series has 84 standard figures and 5 EX Baltans, but I still need to double-check.
Ok, I don't think I've described it before either, so the last thing I'll cover for now (whew!) are the EX and SP designations, the most common alternate "numbers". EX figures are generally standard figures and released at retail just like any numbered UMS figure. For some reason or another, Bandai decides that they need to be set apart from the general collection. Usually, it's because the kaiju is an alternate version of an existing numbered character (Baltan 2, Baltan 3, etc.) or has only limited appeal or a temporary merchandise tie-in (Arc Bogal has only shown up in manga and some DVD shorts based on those stories, not in the Ultraman Mebius series or films).
SP figures are among some of the exclusive Ultraman figures released. The most common SP figures are movie-exclusive characters (check out U-Killer Saurus or any other Mebius movie villain). Next up are Ultraman Festival exclusives, often mere repaints (purple Takkong), sometimes remolds (Chandlar, King Joe Black 1), and occasionally brand-new molds (Armored Mephiras). Even more elusive are store exclusives, figures cast in variant colors or clear plastic or both (Ito-Yokado Eleking).
Magazine and online store exclusives are the most pain-in-the-butt to obtain, but their tags often have no proper designation, the store's logo in place of the number, or no tag or designation is even provided. Some, like the Yahoo! Japan Gomora and EX Gomora set, were given the SP designation.
