When you have completed 100% of the game and defeating O2 go to the 'Options' menu and then 'Theater' and select 'Project K-64'. You will now see the credits with sketches of the characters doing actions before the coloured version happens.
Unlock Evil Kirby: Collect ALL enemy cards, ALL Crystals and then win the Boss battle.
Unlock Bonus Modes: Collect ALL the crystals in the game until the status on the saved game selection is at 100%. Options for Boss battles and an intermission scene display will then become unlocked.
High Mini-Game Difficulties The higher difficulty settings for the mini-games are unlocked when you 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.
Extra Lives: Get the star at the beginning of the level to get an extra life. Then press 'Start' and select 'Try Again'and go to the same level and return to where the star was to get another extra life. Keep repeating this as many times as you want.