And last how do I do the Bob-Bomb and Yoo Who Cannon attack on that block lady and in the Challenge Node? The Bob-Bombs are hard to aim and there is nowhere near enough time to memorize Mario and Luigi's location after thet hit 48.
For the Yoo Whoo Cannon attack in the Cholesteroad, try to memorize the locations of only one of the brothers. Also remember that there are a certain number of combinations that the brothers can be in. One of the more recognizable ones is the "Y" combination, where one brother appears in the top left, the top right, and the bottom middle cannons, while the other brother appears in the rest of the cannons. Let me elaborate further:
X = Mario
O = Luigi
XOX
OXO
OX
This is a rough sketch, so please don't take it as a precise diagram. I found it easier to memorize Mario's locations because his red cap and clothes are rather easy to spot out for me.
For the Bob-Omb Blitz attack on Broque Madame, try to place the Bob-Ombs a little under Madame. There is 1 spot that she goes to that can guarantee that you'll get all of the Bob-Ombs you place to hit her, though. That spot is at the very bottom of the field. Once she goes there, quickly place all of your Bob-Ombs to the bottom-most part of the field and they'll all hit her. Here's a diagram:
B = Bob-Omb
M = Broque Madame
____________
B
B
B
____________M
Move all of the B's to the bottom.
There's also another spot that Madame goes to that will almost guarantee that all of your Bob-Ombs will hit her. That spot is at the top of the field, but if you place one of your Bob-Ombs at the very top, it will fail to hit her, so try placing all of them slightly under the upper-most part of the field, like so:
v Upper-most part of the field
------------------------------
BBBBB M
_________________
Other than that, all I can say is practice and keep trying. If you need more elaboration, feel free to ask. Good luck!