I hated onesies and I know a lot of people that do. You assume that babies need onesies so you buy a ton with cute prints and then you realize that it’s just an extra layer to lift up whenever you change a diaper, an extra layer to change whenever they puke and babies hate having things put over their heads.
You’re better off just buying a thicker PJ for days that are cold enough to need a onesie. And if you really do need two layers (rare), even putting a thick PJ on top of a thinner PJ is less annoying than having to pull something over their head and snap buttons.
Diaper Rash Cream