The images were originally uploaded to Super Mario Wiki. As such they fall under the same copyright as they did on the original site. That copyright is Fair use.
The images are screenshots or promotional photos of a copyrighted Video Game. As such, the copyright for them is most likely owned by the company or corporation that produced them, Nintendo. That use of a limited number of web-resolution screenshots for identification, hosted on servers in the United States, qualifies as fair use under United States copyright law. Any other uses might be copyright infringement.