Wayback Machine has been a godsend when it comes to finding information from previously closed down sites. Once more, it has come in clutch in securing information about the TCG. Below are products of what has been saved from back in the day, along with a bunch of downloadable content that is related to the Inuyasha TCG (like Event Manuals, Judge/Volunteer Rewards Program, etc etc. Sadly, the Inuyasha TCG Board did not get saved even a single time.
Inuyasha TCG's Home Page - You can scroll through the dates one by one at the top or click around in the top banner here to specific dates!
Inuyasha TCG's Card Library - All cards are listed, however, the links within do not work. Additionally, you can only receive the "all cards" result, thus that is what is linked here.
Inuyasha TCG's FAQ - Sadly, nothing too useful here, but linking anyway.
These were all just the important ones that I found. There's tons more. I'll let you do some searching as well if you want but I did preserve as much as possible and put it here.
Here is a link to Wayback Machine's homepage where all of this is possible from. Enjoy!
Attached below are additional useful and interesting documents from the website that have been downloaded and are hosted on Google Drive (in case Wayback Machine ever closes its doors). The files take a bit to load sometimes. I can't do anything about that. Sorry!