Well, as the title says, there is a glitch in Multi-Man Smash that makes the final CPU in Multi-Man Smash HUGE.
How to do it:
It's simple, beat all the Mii's then make it to the last Yoshi. After that, keep pressing the B button to swallow the Yoshi and put the Yoshi in the egg. The Yoshi will get bigger everytime it gets out of the egg. Keep doing this until the Yoshi can't fit in the screen anymore
Here's a video if you're still stuck on how to do it. Made by me