Yo-Kai Watch Blasters: Red Cat Corps/ White Dog Squad will be released for the Nintendo 3DS family next week on 7 September 2018, and while you have to choose either Red Cat Corps or White Dog Squad, either purchase entitles you to a free Moon Rabbit Crew DLC.
Interestingly Nintendo of America posted on their Tumblr that the Moon Rabbit Crew update will arrive on 27 September before quickly removing the date. Maybe it is a misfire, maybe it is not, but Moon Rabbit Crew DLC will definitely be arriving for free for players of Yo-Kai Watch Blasters.