Wiggler glitch
The Wiggler glitch allows you to accumulate lots of 1-ups and points and potentially max out the counter.
To perform this glitch, you must go into Forest of Illusion 1 with a cape. Go forward until the wooden platform with the three Wigglers. Now, bounce off them repeatedly. While they will turn red and get all angry, if you leave the screen and come back they will be all calm again and you can continue stomping on them. You will get points, then 1-ups, then coins and afterwards the game will glitch and you will get huge amounts of coins, 1-ups and points. If you do this long enough you will eventually reach 99 lives and a score of 9,999,990.
P-Switch Recycle
To get this glitch to work correctly, you must be riding Yoshi. Yoshi must press the P-Switch and eat it before it disappears. When Yoshi spits it out, the P-Switch will be back to normal and you are able to press it again.
Glitch Key
To make this glitch, you must have already pressed the Red and Green ! Switches. You must have Cape Mario and a Yoshi in Star World 4. At the level's secret exit, they must make Yoshi keep the Key in his mouth and fly with Cape Mario to hit all green ! Blocks at the left. If you drops the Key, it will be an item that changes from a Yellow Beach Koopa and an upside-down Cheep-Cheep.