Yoshi's Island: Super Mario Advance 3 Cheats

Grab a Melon Bug (the creature that rolls up into a ball) 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.

In any World, whenever you get your World Score to 777, you will earn 7 lives.

After you have gone over all the hills there is a pipe that ‘Shy Guys’ come out of. Ignore them and go past the pipe and get rid of the Killer Plants in the next two pipes to the right (one above and on the ground). A Kooper is walking between the two pipes on the ground. Jump on the Kooper and send his shell spinning between the two pipes. ‘Shy Guys’ continue to jump out of the pipe on the left and every time the Kooper shell hits them you will hear a different sound that means you’re getting lives! Stand on the pipe on the right and the lives will continue for as long as you stay on this screen.

Beat the game to get a whole new set of 6 levels not found in the original Yoshi's Island.