He's first seen turning SS2 against Cell, but obviously, Goku new about it, so when did it happen?
DRAGON BALL KAI IS BEING CANCELLED IN JAPAN BECAUSE A NEW ANIME IS TAKING IT'S TIME SLOT ON DREAM NINE. IT ENDED IN THE CELL SAGA AND WILL NOT CONTINUE INTO THE MAJIIN BUU SAGA. THIS IS NOT A JOKE! FUNIMATION WILL DUB ALL OF THE CELL SAGA, BUT AFTERWARDS, IT IS OVER!
I'm just thinking, what if Goku and Vegeta had the oppritunity to fuse and beat Cell? Would they win? Would Vegeta do it?