Next Level Games is an independent studio, apart of working with Nintendo every now and then they are no ties between them and Nintendo.
That's not true at all. Nintendo revealed a program called venture fund which is an initiative for satellite developers who create first party content for Nintendo. The details are of course not for our understanding, but it's some type of program that keeps a certain amount of willing developers constantly pitching and working on projects for Nintendo. Alpha Dream, Skip, and surely these western studios that always make games with Nintendo SPD.