Unless it has changed a lot in the past couple of years, psych and PM and R are easier to get than internal medicine.
IM at one of those very few "top" programs would be fairly comparable to trying to get a spot at any/random derm program, but probably a bit easier in the sense that they might accept someone with a slightly lower USMLE (like 220's) if the other required things were in line (i.e. the person has good grades and good research). For derm, there is more of a narrow scope of what is acceptable, even for a lower tier program, just because there are so few spots and so many people who want them. If someone applies broadly, and has average or better USMLE's and pretty good grades and honored the medicine subI, and maybe a little bit of research, and good LOR's then I think to get an IM spot at a very solid academic IM program (but not on the level of a UCSF/Harvard/Hopkins type of place) should be possible. I'm talking about the UAB/Baylor/Emory/U of Rochester/Vanderbilt type of places. And this is if you aren't totally married to having to go one particular place, and you interview well.
Psych, even at some of the mid upper tier academic type hospitals like I mentioned above, often will take IMG's, etc. with good USMLE scores, so it tends not to be hard to get for US grads. If you are talking about psych at whatever the top 5 most famous psych places are (I have no idea) that is in some popular/preferred city on the East or West coast, that might be different.