Cappy is the first boss, and he's not too hard. He'll hide under his mushroom cap and try attacking your paddles. Just hit him and he'll soon throw off the cap and call on some smaller cappys to shield him. Knock out the small cappys, and knock him out.

Squishy doesn't have any threatening attacks, except if he can, he'll catch you ball and try throwing it at the spikes.

 
Kabu isn't too hard, it's just his smaller kabus you have to watch out for. You have so long to try and beat him, before six kabus will come, launching themselves in every direction. They will keep re-appearing until you knock this boss out.

The only disadvantage you have is the platforms blocking your aim from Poppy. Just try to focus on getting it to where the top paddle (and the sides) do most of the work. He'll throw bombs trying to immobilize your paddles, but otherwise his days are numbered.

It starts with Mr. Shine, who you have to try and hit as much as possible (hopefully enough to beat him) or else he will throw stars at all the paddles immobilizing them. Knock him out, to set the stage for Mr. Bright, who will throw fire balls and such. Keep smashing him and he'll finally bust. By this level, you'll probably have the stone ability, which can help your hits be alot more accurate.

Mr. Frosty knows what you intend to do, and he is going to be stubborn about letting you win. He'll stand still, but if you hit while he's doing this, he'll grab your ball and throw it. He'll quickly shuffle to the left and right trying to knock out your paddles, but try and knock him a.s.a.p.... as this is the only time you can do so.

His only real threatening attack is his lightning beam, which will immobilize your paddles... it's unavoidable. Just try and keep hitting him and paddling your ball with small paddles.

Whispy calls on the help of Gordo aide him in this fight. Gordo will drop from his branches and try and stun the paddles, and then Whispy will try and spit out puffs in defense. 12 hits will stump this tree.

Kaboola's flying ability won't help her here, but cannons make up for it. She'll shoot off cannons in directions, but that's almost about it. Just keep knocking her.

This robot is heavily secured with the platforms making your aim hard. Try to have an ability, which can help. He'll try to knock out your paddles, but again, just keep knocking him.

This is the "hidden" level, and to get to King Dedede you must have beaten the border line on every world.
You'll see King Dedede in three forms here: 1) He'll throw bombs 2) Will swallow the ball if shot at him from below 3) He'll shoot rockets at every paddle. Just try to overcome his attacks and finish him off.