Ok I got pass Star Hill, so can someone please tell me how to defeat princess..

Well first of all get more of those mushroom that gives you life back and power.you might want to get alot of idems like shells,chain chomps,trampelines,and stuff because the first princess shroob is already really hard to beat so make sure you have alot of idems

I did it by practising my dodging and just lvd up

Okay, for the first sister, you're going to mainly need good dodging, and tons of Ice Flowers because they will quickly get rid of her shield and kill her when she's vulnerable. This batlle will take a while because of her high hit points amount. Be careful of when she fires lasers and stuff at you. They deal lots of damage.

For the elder sister, also use Ice Flowers. But be weary of those UFOs because you don't want the number to reach zero (put simply, you die). When you hit her enough, she will turn big and have multiple functioning body parts. This is the easy part, use as many Mix Flowers as possible and not only will it deal tons of damage, but it will destroy different harmful body parts (arms, legs, etc.). You'll eventually win and then you have to face the easiest battle against Bowser, then the game ends.