To get to peds derm, one has to go derm-->peds derm, as peds derm is under the American Board of Dermatology rather than the ABP. So it's "competitive," in the sense that you have to match to a much more difficult to attain residency first
Peds fellowships generally aren't that competitive, but if I had to pick one probably pediatric EM. Peds cardiology is a little more competitive as well.