Mario kart 8 is running in 1080p on a docked switch, the wii u version could only handle 720p which is a 2.3 x increase in pixels. Now the wii u gpu has a performance of 176gf, times that by 2.3 and you get 405gf. So the console has to be a minimum of around 400 gf to be able to run mario kart 8 at this resolution.
http://www.gamespot.com/articles/mario-kart-8-nintendo-switch-resolution-and-frame-/1100-6446930/







