I think the most important qualities that all the Disney Princesses share are their moral values and love for others. It's also important to never give up, to treat others as you would like to be treated, and to be passionate. Apart from being royalty, all the princesses have their eye set on some kind of goal (ex: going to a ball or finding adventure), a hobby they're passionate about (ex: painting or collecting artifacts), and a really strong love for someone in their life (ex: significant other or a family member). An animal sidekick is a bonus lol :)
Aurora, Tiana and Rapunzel are the only ones who wear crowns. You could say that Jasmine is wearing a freestyle untraditional tiara simply because she has a royal jewel in the middle of her headband. But that’s it. The others do not wear crowns. Sorry this was @MsPotato