I let myself see Ross Andru and Mike Esposito on Dell's Monkees#1 but at least after "Lee" and Mark Evanier correctly suggested Mo Marcus, that led me to more Marcus IDs elsewhere. If anyone has a better idea on this funny animal art than Andru and Esposito, I'd be gratified to hear it.
"Outboxed the Boxer," the first story in Tom Cat#4, April/56--the first issue; yes, Charlton, why do you ask?--is drawn in a style not used in the other stories in that issue or the rest of the 5-issue run. The later issues are by Al Fago, who signs a cover and a story, and perhaps other artists in his style.
With the wildly different, comparatively "realistic" style of this first story, I'd think that it was another one of those examples of Charlton's buying up the inventory of a defunct company, but the writer, whoever it may be--"Ngaaa!" and Kurrash--continues on the feature throughout the run.
I'm guessing Andru and Esposito more by the inks than the pencils. Although this is a comical comic book, the figures aren't in the industry-wide "make it look like Mad but not anything actually like the Madartists" style that Andru used on Get Lost.