If it's like Kevola said, yeah, Nosepass won't be in it but still, NU have some great shiny if you put just those with a good usage. And you won't have shit like rattata or caterpie.
Maybe one more con, it could be less interesting to enter a big tourney series like The Legend of the Steel Bird. Or maybe I just say shit..
@LifeStyle read kevola's idea, it could be what you need.
You know what I mean, don't play stupid. NU tiers have more bad shiny than others, just that. But yeah, you could also have a big one like Nosepass or claydol.