All those test were done with an really old build of the WiiU version(E3 Build). None knows if the final version of the WiiU got better or not.Here's a list I saw of how the game runs across versions.
>Switch runs at ~25-30 fps docked, 30 fps handheld
>Wii U runs at 15-30 fps
>Switch runs at 900p docked, 720p handheld
>Wii U runs at 720p
>Switch has effects and shaders while docked that aren't present while handheld
>Older Wii U footage did not have those shaders
>In terms of GPU, docked switch > handheld switch > wii u