From Don Markstein's Toonopedia, I have copied comments about the other artists that worked on Scorchy.
"stand-out was Bert Christman, who later co-created The Sandman for DC Comics. The next outstanding cartoonist to work on Scorchy was Frank Robbins, who, like Sickles, had never had a feature of his own before. His signature first appeared May 22, 1939. Robbins packed the strip with hair-raising adventures, but he didn't stick around very long. In 1944, he was hired away by King Features, where he created Johnny Hazard — practically a clone of Scorchy."
Then there was another succession with, again, one minor stand-out — George Tuska (Buck Rogers, Crime Does Not Pay and other diverse credits) served a stint during the 1950s."