3DSMAS Pros:
I can play Galaxy on the go
I finally get to try Sunshine
Online multiplayer in SM3DW
3DSMAS Cons:
No galaxy 2
No Pro Controller support apparently
No Widescreen for SM64
No Co-op like what was originally planned in SM64 (until further notice)
IDK entirely, I've only found one source that says no but for Galaxy, I can kinda see why, unless gyro would work for the pointer or another way to grab the star bits after being launched from a launch star, using the right stick would work in that case tho.