Yoshi's Island Cheats

Bonus games:)
Press and hold Select and push L, L B, A, R in the level selection screen. You will see a  list of bonus games will appear. If you win the chosen game you will get a prize.

Get Bonus levels:)
After finishing the game, an extra level for each world will appear.
 

Finish all eight levels in each world with a 100% completion to unlock a ninth level in each world.

Hard mode:)
Get 1,000 points in a world (100 points on all ten levels including Extra and Secret levels). A star will appear on the game selection screen. Get five stars on that screen to unlock hard mode.

Alternate ending sequence:)
Finish the game in hard mode.

Lucky 777:)
Get your total points for a world to equal to exactly 777, to get 7 extra lives.
 

Special Yoshi eggs:)
To get special Yoshi eggs with out having to find special boxes, fire a Yoshi egg in an area that will cause the egg to bounce off the walls and back to you. When the egg returns to you, quickly use Yoshis tongue at the egg. If successful, you should have a special Yoshi egg.
 

How to beat Naval Piranha Plant with one egg:)
When you arrive in the Boss room where that small plant is located, step on the first block on the platform, then shoot a egg at him. However, do not go further than the first block on the platform or Kamek will appear and turn that small plant to a huge monster.

World 5-4 - Free mini-games:)
Go to a door on your left. Use a POW block or "?" and go to the door and get the secret code. This code will give you free mini-games when you go to the level selection screen.

Get unlimited lives in Touch Fuzzy Get Dizzy:)
If you take a Melon Bug, which is the creature that rolls up into the bug, and go to the pipe with Shy Guys jumping out of it. Spit the Melon Bug close to the pipe on the left-hand side. When Shy Guys jump out, after a while you will get a 1-UP for each time a Shy Guy hits the Melon Bug when it is in its melon form.