It seems completely random, and it would really defeat the existence of doing a Waddle Dee part to begin with. This one only make one true fight.
I say if it's not recreatable it should be banned. If in the future a consistent way of doing it is found, we can go from there.
^ No, the runs are short enough as it is. It is a glitch that adds nothing cool or clever to the run. Besides, Wouts already made it against the rules. You also don't even run the game.
So after recently doing some Mega Man runs I actually came across this 'glitch' myself and I discovered tha it's actually not a glitch but it happens every time you tap 'F1'. The user who found it probally wanted to reset using esc but acidentally pressed F1 and thuseforth activated the 'glitch'. I don't know if anybody else discovered this but I'm putting it up here that everybody knows
