Well, I was playing a hack of Super Mario World and found 2 Yoshi glitches. Note: These are not well-known; maybe even newly discovered(that is a very small chance since millions had played this game) so there is probably no glitches you are expecting(I think). These are only minor glitches and will not effect your game.
 First is the Yoshi Spring Glitch. To do this glitch, you need to press the run button and spin jump button on the controller. It seems to help me when I also press up on the D-pad. When you do this, you will spin jump off Yoshi and go to the top of the screen(off screen depending on camera and height). It's not as effective as if you jump off Yoshi in midair though. That means it's kinda useless but if you are bad at timing then this may work for you. It's also a little cool how he jumps that far up since it's on the ground. Recommended on emulator for better times.
 Our next glitch is Yoshi Dance of Doom glitch. YOU NEED EMULATOR OR RIGGED CONTROLLER TO DO GLITCH. Sorry for shouting. Anyways to do the glitch get on a Yoshi and press left and right at the same time. (This is the part where you can't do it on a controller since you can only push the D-pad in one direction. Doing it anyways risks your controller of being broken.) When you do this Yoshi looks like he/she is dancing. It's not as useless as the last one since holding the run button makes you go faster than when you start running. One side-effect is that when Yoshi is dancing, he can only go right. This makes it a little hard to control unless you have good reflexes or skills or just get used to it. Also watching Yoshi dance is amusing :3
 Anyways that ends my glitches for Yoshi. Try them at home! If you have any glitches too then post below. I will try them out! Thanks for listening for me blabber about two glitches. Have a good day!