Trying a circuit and looking for guys who weren't picked up by WWE and didn't sit out there contracts I got
AJ Styles Air Paris Alex Wright Bam Bam Vito Kash Crowbar Disc Elix Skipper Karagias Duggan Harris Bros Jarrett Kaz Konnan ( not sure if he sat out) Meng Ice Train Reno Douglas The Wall David Flair Vampiro Muta
Meng should not be on that list, as he left WCW with the Hardcore Title and showed up briefly in WWF (as Haku), so wasn't on their final roster.
You can add at least the following: Dewayne Bruce (Sgt. Buddy Lee Parker), Kwee-Wee / Allan Funk, The Demon (Dale Torborg). Not sure how you want to handle guys like Norman Smiley who never wrestled for WWE but have worked for them.