Yersinia enterocolitica does express flagella at a temperature around 25°C, but not at 37°C. Kapatral et al. Besides that it can rely on peristaltic movement in the intestines.
Yersinia pestis is as far as I know nonmotile in the host, but motile if isolated Medical Microbiology.
As there are some other Yersinia species, including Y. pseudotuberculosis of course, I think you cannot totally generalize the answer for Yersinia spp., but searching for the Yersinia of interest with "flagella", "motility", "movement" or similar keywords on Pubmed might help.