How do you beat Princess Shroob?

You should have more 1-ups and recovery items to beat her. When she glows it means that her HP is low. I don't know how much HP she has but then after you beat her there's her twin sister you have to fight. After fighting her for a while, she'll do something with her crown that makes her big, gives her tentacles and legs. You have to take out her feet, then attack the crown. It has a max HP of about 200. Once the crown is deactivated, you can damage her. She doesn't have as much HP as you would expect her to. You should have a higher level, focusing on upgrading HP and attack more. It did take me a while, but I got it eventually.

Here's a tip. Fight like you usually do, but try to be more defensive. Practice your defensive attacks here, because you'll need some skill when you face her when she glows. When she starts to glow, she'll start moving faster in her idle state, and she'll attack a lot more than usual, sometimes 3 times per turn. But she's close to losing, so hang in there! Use healing items if needed. Keep attacking and defensively attacking (this helps a lot) and when you think you are close enough to her death, go all out (but not too all out, you need to save items for the next battle). Don't worry about health, just worry about power, because you will get healed after you beat her. Then prepare for the bigger, harder Princess Shroob. She's a lot more complicated to explain, so I'd check matt c_1's description or walkthroughs.

To destroy her sheild more quicker, use the copy flowers. And if you wanna destroy her, six words: your going to need more mix flowers...

To defeat the first shroob princess, use smash eggs to break her shield, then use fire/ice flowers to finish her. Use ice/fire flowers to defeat her twin also. I would also recommend the badge that gets you HP the more damage you do to someone. You can get it from the present princess peach's castle store. Although it is the most expensive badge, it is absolutely worth it.

Look for patterns and laughs