Wakachan died a long time ago now, around 2016 probably. To my knowledge little of it was archived. A few of the boards that were part of the network survived, but not many, most were already dead by then. They were later united under a new Idlechan site at idlechan.net, which died shortly the same year. All locally hosted boards except the general "board discussion" and the site banner board were archived by the admin, and uploaded to archive.org much later by killsushi. Shanachan survived for another while but then also died. Part of it was archived, but only the fetish board (thanks to Bozek for that). A few other boards survived.

Archives:
Last Idlechan archive: https://archive.org/details/idlechan-boards
Shanachan fetish board: http://bozek.cz/shanachan.org/
Surviving boards:
Azumanga board: https://ib.axypb.net/azu/index.html (features an archive of all the old /azu/ threads from Wakachan)
Dictators: http://www.mufunyo.net/dic/ (one of Wakachan's last surviving original boards)
/tan/: https://kakashi-nenpo.com/tan/ (this one and the one after were made for idlechan.net I think and were not part of the original Wakachan, though they're based on older boards)
/snow/: https://kakashi-nenpo.com/snow/
There might be a few more still around.