How difficult is internal transfer to CNS? (NOT CS)

I’m specifically looking at CNS mathematics; applying for fall 2019 internal transfer from UGS undeclared (I’m co 2022). I’m NOT looking at CS. CS is a shot in the dark even with a 4.0 or so I’ve heard. There also is the possibility that the people who don’t make it into CS are making math transfers more competitive. And there are plenty of CS hopefuls that don’t make it.

Mainly, I’d like to transfer out of UGS asap. Being undeclared is risky.
So difficult is it to internal transfer into CNS mathematics, and how does it stack up against other CNS majors such as Biology, Chemistry, etc…?
How holistic is the entire process? The website states that they evaluate GPA and the internal transfer essay.