http://tcrf.net/Tetris_%26_Dr._Mario
"Nintendo re-released the standalone Dr. Mario game in Nintendo Power and BS-X variants. Only difference being Nintendo removed the B button command and dropped you at the Dr. Mario title screen; however the full Tetris & Dr. Mario game still exist even right down to the options and debug menus. To start at the Tetris & Dr. Mario copyright screen, use the PAR code 80802D01.
(Source: nensondubois)"
This video shows the PAR code being used to load up Tetris.
It is also recorded in the newly-released snes9x-sx. Download it here!
http://bsxproj.superfamicom.org/