Upvote:5
Russian Wiki features a list of the repressed highest officers (some of them were prosecuted not in purges but during the war). Unfortunately, the English version does not exist.
While there is a Wiki page for each officer mentioned, the corresponding English pages are rather sketchy. Also unfortunate.
Anyhow, I skimmed their personal information, and it is safe to assume that virtually everybody in that list born before 1897 served in the Imperial Army in a certain capacity during WWI or before, mostly as junior officers or sergeants. There are a few exceptions, most notably Iona Yakir, who was drafted but served as a turner at a military installation.
It is worth mentioning that many non repressed commanders, such as Shaposhnikov also served at quite high ranks in the Imperial Army.