You know, it feels like every Marvel teen hero issue the last few months have been character crossovers when they weren't busy with CWII. Probably due to wanting more people to pick up the Wasp and Riri books since seeing them in Moon Girl etc might make people want them(haven't worked thus far as far as we've seen). Ghost Rider is such a thinly veiled "Do you want to pick up a All-New Fantastic Four later?!" book in this first arc.
Moon Girl already had Kamala and Riri is coming
Riri is about to have her enter the MU whole
Nadia is gonna have MG in Issue 2
Ms Marvel herself had Nova and Miles by issue 6
It goes on...
I think they want some books to get a rub from the guest stars and its readers.