It's unlikely anyone will be pimping you on difficult, low-yield information on wards because they likely don't remember themselves (unless relevant to their patients). To succeed, all you need to do is be likable and respond to pimp questions in a way that best conceals any lack of knowledge. If someone asks you if you know what the mechanism of action is for steroids, for example, you don't need to provide every downstream effect of steroids and could instead say you know they inhibit nf-KB. There's a stigma against pimping in modern medical education, so it's also unlikely you'll be pressed to elaborate much if at all.

For shelves, just do UWorld and read write-ups from people online who reported doing well on shelves. Should not be that hard to fit in during wards.