In 1999, two upstart hardcore wrestling promotions started based on the success of ECW. Those were CZW and XPW.
Former ECW tag team champion, John Kronus, was the only wrestler to appear on shows for ECW, Combat Zone Wrestling (CZW), and Xtreme Pro Wrestling (XPW) in the same year. That year was 1999. Kronus was the longtime tag team partner with WOO-involved wrestler Perry Saturn, with their tag team known as The Eliminators.
According to his bio on Cagematch (https://www.cagematch.net/?id=2&nr=976&page=4), here are his matches of significance in 1999:
ECW
- January 10, 1999 - On the Living Dangerously 1999 PPV, Sid arrives and defeats Kronus
- February 13, 1999 - Taz defeats Kronus for the ECW World Heavyweight Championship in Poughkeepsie, New York
- March 5, 1999 - Kronus' last match was a tag match (with Spike Dudley) losing to the Dudley Boyz in Dover, Delaware
CZW
- May 22, 1999 - Kronus' first match in CZW. He lost in a 4-way match for the CZW heavyweight championship at the CZW Arena in Mantua, New Jersey
- May 29, 1999 - Kronus' 2nd match saw him lose a 3-way match at the Gaetanos Indoor Soccer Arena in Malaga, New Jersey
XPW
- October 29, 1999 - Kronus' first match in XPW saw him eliminated in a battle royal for the XPW World Heavyweight title at the Reseda Country Club in Reseda, California
He continued on with CZW and XPW in 2000, but he never returned to ECW before the company stopped running shows in 2001. Kronus' last match saw him lose to felloe ECW alum Balls Mahoney on November 5, 2005 back at the ECW Arena (then called the New Alhambra Sports & Entertainment Center) in Philadelphia at the "Hardcore Homecoming" November Reign event.
This video shows Kronus in 2000 in a XPW in a 3-way match with Supreme and ECW alum Axl Rotten:
This is one of the few interviews with Kronus discussing some of his pro wrestling career: