At the title screen hold L,R and Z, while holding those push the A button and Kirby will say ''hii!''
To access the higher difficulty settings for the mini-games, you must beat the difficulty setting before it. In the beginning, beat the Easy setting to unlock the Normal level. Beat the Normal level to open the Hard level. Then, beat the Hard level to access the Intense difficulty level.
In the beginning of a level go left as far as you can. There should be a star or a cake, rib, etc. After you get it press start, do try again and keep going back to get the thing. It will always be there!
You can boss battles by beating O2.
To open up the secret planet Dark Star, collect all 100 shards and beat Miracle Matter once more. Dark Star will open up. At the end of the planet, you will fight the TRUE final boss, O2.