Cell: Kaioken

[Cetra]

Of course many things were never actually used in the story so it could go in exactly the direction it was supposed to go but still I wonder:

Shouldn't Cell be able to use Goku's Kaioken?

Imagine if he would have used it together with his Kamehameha in the first place. Even while being distracted I don't think he would have been overwhelmed by Gohan. Or using the technique before would also have been smart and better for him to compete with Gohan instead of trying out desperate moves.

[Gonstead]

IIRC Cell does mention that he "knows all of his (Goku) moves, from Kaio-Ken to Spirit Bomb" when speaking to Piccolo.

[Cetra]

I remember that line different (like: "and even more, Kuririn! even the Genkidama!") but my manga is not English so that might be the reason.

That is suspicious if you ask me. He should have used it and not go all rampage Cell, even though it is very Vegeta-like (but even Vegeta uses something good if he knows he can do it), when fighting with Gohan and losing. Generally the Kaioken was just not used anymore because it would have been overkill and boring, not just because it was so hard to handle for the own body, if you ask me. Remember Goku using it more than once against Vegeta even though Kaioh said no and still he increased his power and survived it. For the few seconds you need to finish your enemy off (which is probably not even the time needed with their speed and when using the Kaioken not at all) it should always be possible to handle.

[KameRule]

Maybe Perfect Cell's power-weighted form he used when fighting Gohan (just before he threw up #18) was reminiscent of the Kaio-Ken?

[Super Vegetto]

Or Kaio ken draws out users dorment powers that Cell didn't had, unlike Goku that had plenty and didn't hit his prime in base after long time...

[mAcChaos]

I assume that Kaioken is drawing out the same power SSJ does. So SSJ is already drawing that power out, but with less drawbacks.

[Cetra]

I assume that Kaioken is drawing out the same power SSJ does. So SSJ is already drawing that power out, but with less drawbacks.

Well if we take the filler episode it does not. And Kuririn was surprised about the Kaioken being like an "infinitely high power" increase before Goku said he cannot use it that much because of the disadvantage (which did not hinder him from still using it, but anyway he did not say the increase was not possible but just that it becomes more dangerous and as we know Goku also trains using his power easier with less disadvantages).

The buff Cell move was not the Kaioken or similiar. It was like Ultra-Trunks as Trunks himself mentioned. Kaioken actually increases (or at least is shown to increase) not just power but speed and Gohan totally beat the crap out of him.

Generally I would say, give Goku, Cell or other Kaioken users that can resist the pain for at least some moments exactly those moments and they can do way more than the story shows. However, of course you cannot show the same stuff all the time.

[Pantalones]

I figure Kaio-ken and Super Saiyan just weren't very compatible with each other (few moments of Super Kaio-ken in filler aside... and even that was with dead Goku who's established as not having as hard a time with straining techniques/transformations as living Goku, going by how SSj3 worked for dead vs. living Goku.)

When Cell powers up, he seems to have "Super Saiyan-like" transformations... he just doesn't physically change much (or at all) most of the time. It's especially noticeable when he goes "Ultra Super Saiyan" in an attempt to overpower Gohan, and later when he goes "SSj2" after blowing up and regenerating he even gets the SSj2-style aura, complete with lightning and everything... but in the anime at least he's also had basic SSj-like auras ever since he powered up to fight Piccolo and #16 after absorbing a bunch of humans, but not before that point (don't know about the manga off the top of my head, though.) It seems like reaching different "base" levels of power (usually through absorption) also unlocks higher "Super Saiyan-like" form levels for him automatically--getting regular Super Saiyan in his imperfect state after maxing out that form's power, then developing the ability to use the "Grade 2/3"/"Ascended/Ultra Super Saiyan" type forms after reaching his perfect form, and then developing his own SSj2 equivalent after coming back from near death.

So Cell probably never used Kaio-ken because he was already using his own version of Super Saiyan, and either just didn't think to combine the two or (if taking filler into account) didn't know that they could be used together at all. Goku didn't seem to come up with Super Kaio-ken until after he died, after all, so at the time Cell got the information on Goku's techniques, the possibility of that combination wouldn't have been in there.