I have most (most of the non-obscure ones anyways) of them, and beaten some of them:
SNES: Super Mario World 2: Yoshi's Island, Super Mario Kart
GB: Super Mario Land, Super Mario Bros Deluxe
N64: Super Mario 64, Mario Kart 64, Mario Party, Super Smash Bros.
GBA: Yoshi's Island: Super Mario Advance 3, Super Mario Advance 4: Super Mario Bros. 3, Mario Kart Super Circuit
GC: Super Mario Sunshine, Luigi's Mansion, Mario Kart Double Dash, Mario Party 5
DS: Super Mario 64 DS, Mario Kart DS, Mario Party DS
Wii: Super Mario Galaxy, Super Mario Galaxy 2, Mario Kart Wii, Mario Party 8
3DS: Super Mario 3D Land, Mario Kart 7
So... 24 I guess, if I haven't forgotten any.
I have but haven't beaten the NES games or their remakes on SNES in any case, as well as Super Mario World. Only two of their handheld ports. Also, none of the four 'New' games have I beaten, pretty far in NSMBU though, and I'm not sure whether or not I've beaten Yoshi's Island DS. I consider Yoshi games to be Mario games. Smash Bros. and Luigi I find debatable but I included them anyway. Also debatable is stuff like 'Alleyway' and 'Tennis' on GameBoy, technically they're Mario games as they have Mario in them, but I didn't include them (don't know if I beat those anyway, if that's even possible).
