Goku Vs. Superman 2

[Dispenser Of Truth]

Ah. I said "watch" but I forgot the anime would have weird stuff like that. But this doesn't go by canon, so fair enough.

Well, there's no reason he shouldn't be able to use the Kaio-Ken as a Super Saiyan. It's not a transformation, it's a momentary technique that he improves over time, and by the time of the Cell Games where he's mastered the Super Saiyan form to where it no longer drains him, he should be able to use them in conjunction (he did for a single attack against Pikkon, calling it the 'Super Kaio-Ken' but it left him drained) and to much higher degrees of multiplication. And I've read (most of) the manga as well; actually, what I haven't seen on the show I've read in the manga, and vice-versa.