Super Mario Galaxy Tips

Beware of Bouldergeist
A lot of people have trouble with him, so here's some of his pros. and cons.

Pros: He can rebuild himself, he can make big rock hands to crush you, he can control rocks.
Cons: It's very easy to tell what his attack is, three hits brings him to his true form, he fires what can lead to his defeat, his attacks are easily dodged.

In his first form, he has two attacks. One is to make a line of sharp rocks appear. You can see that it's coming when shadows form on the ground. When they're up, star spin to break them. His second attack, the key to beating him, is to throw rocks. He has three different types of rocks. Gray rocks, which do nothing but hit the ground if you move out of the way, gold rocks, which gives coins (aka health) when they don't hit you, and black rocks, the most important, which brings a bomb boo onto the field. Star spin near it and make it hit Bouldergeist. Three times and he'll show his true form. And keep in mind that when any of the rocks hit you, you get hurt. In his true form, he'll run away from you and drop bomb boos in his path. Grab one and hit him, and he'll be in his rock form again, only now with two large hands. Two hits breaks the rock hands, much like himself. He has two new attacks, and he'll add an extra line of rocks. One new attack is that he'll punch you with one hand. He won't turn around while punching, so it's easily dodged. Another thing is that he'll raise his rock hands and bring them down to crush you. Just stay out of the shadow and you'll do fine. Rinse and repeat and get that star.