Oh, forgot to mention. Yo-kai Watch Busters 2 hasn't been announced anywhere. What we have is early leaks from a magazine (presumably CoroCoro, Famitsu has never had Yo-kai Watch scoops, which makes sense since CoroCoro is one of the partners for the series), so it's either:
- leaked scan don't show the platform
- it's just a teaser, with the actual reveal coming next month
Level-5 is yet to announce anything, so it's no wonder we're missing key details here.
And as we all learned in the past few years (I know, I've been there myself with EOV and DGS2), lack of platform at announcement doesn't mean much. It's not like the Switch is a super secret thing you need to stfu about or you get the nintenjas sent after you.
As LordKano said, YWB2 is most likely a 3DS-only, and I'd add it's definitely releasing alongside the 4th movie in December.