u cant, but a half decent pc or phone will do it just fine, i use Azahar on pc and it runs perfect

or u can use artic base if you want to play 3ds on a bigger screen, u still need a pc or a phone tough

if u have an old 3ds u can use artic base for o3ds->pc and moonlight for pc->wiiu but if u have an n3ds u can use ntr stream and directly stream ure 3ds to ure wiiu (u have to download ntr view on the hb app store on wiiu)

u actully can just download an 3ds emulator that supports wii u

You cant because the wii u uses a different chip instead of the 3DS which uses a similar chip to mobile phones ones so no, you cant in ANY way unless you buy a console from the 3DS family of consoles.