Which big game has sold the worst?Well we haven't really had any developer come out and state they were dissapointed with sales. I mean I could see Skylanders and Just Dance underperforming, but Activision and Ubisoft both have came out and said they have games they are developing for the Switch that will be announced soon.
I guess you could consider ARMS as the worse selling but that still sold 200k+ in Japan and 300k+(with digital) in US which for a middling reviewed new fighting ip is pretty decent(it's also a game that Nintendo I'll try to support for a while).