mmm… Dean’s would be super baking, like… he just has magic hands (no pun intended but ok baking and sex magic hands :P) so things just WORK for him, he still has to put effort in but things just come out that little bit better or if he accidentally puts a pinch too much salt in it magically sorts itself out and adds a little nutmeg cos that would make it epic!
Sam’s would be that he’s an empath and can tell what people are feeling by touching them, it just adds to his inherent empathy but it’s really damn useful both in personal and hunting scenarios, plus it makes him damn good in bed 😉
Cas’ would be the ability to talk to animals 🙂