Humans and Piccolo had learned Kaio-Ken?

[Ultimate Cell]

[mention]SuperSaiyan2[/mention] challenge. So in this scenario King Kai actually decides to teach the kaioken technique to the earthlings and piccolo while their were at his place. How do things change?

 

[Boo Brand Milk]

Piccolo bragged to Android 20 about unleashing their power in extreme burst. I took this as they already developed an equivalent technique during the 'three years.' Piccolo was ssj tier at that point and this provides a decent non-asspull explanation.

 

[Captain Cadaver]

For the earthlings, it wouldn't change much going forward when Kaioken x20 would still be far from on par with the SSJs (and it's hard to say if they could develop beyond Galu's peak with it). With Piccolo, on the other hand, it may be an absolute game-changer if he utilises it right. With Namekian regeneration possibly being a way of mitigating the strain of Kaioken, he could potentially bring it to far greater levels than x20 at the cost of more Ki loss.
In any case, one of the lower levels of Kaioken would allow him to completely catch up to Gero when he attempted to flee and he kills him before he can get to the lab. Trunks then advises everyone to find Gero's lab and, once they do, they destroy it completely. Kaioken is enough for Piccolo to easily kill Cell after he gets his explanation before Cell can attempt the Taiyoken, so the Cell Arc's battles come to an abrupt end. Trunks then gets the plans from the underground lab and stays a while to train, Goku bringing up the Rosat which everyone eventually goes in at some point. Trunks then returns to his future.
I'll say that the training from the Rosat would've provided Galu there was some knowledge of a state beyond Super Saiyan as with him having confidence in the potential power of Gohan's rage, with he and Vegeta achieving SS2 during the timeskip. When the Boo Arc happens, either Goku, Vegeta or a Kaioken amped Piccolo quickly deals with Dabura and averts the entire battle with Boo.
The start of Super goes otherwise the same with Beerus not being pissed off enough to destroy Earth, yet still insistent on discovering the Super Saiyan God and starting a fight because of that. Kaioken x20 or higher may stop Piccolo being beaten around by Tagoma, though Freeza still kills him all the same. In the Universe 6 Arc, Piccolo's gains combined with Kaioken allow him to oneshot Frost, Magetta and Cabba before facing Hit, who even if winning, would be forced to use his full power and just get beaten by Vegeta anyway. Piccolo beats a sizeable amount of ToP contestants on his own and perhaps Tenshinhan would avoid being fodderised so quickly too, though it'd be only a matter of time for Ten and Piccolo would still be caught off-guard like he was in the series . Due to not being tutored by Vegeta, Cabba nor Caulifla would have SSJ, meaning both are eliminated long before Potara fusion with Kale becomes an option, making Universe 6 eliminated far quicker. Gohan not stalemating with Kefla allows him to help out a lot more against Jiren, making Universe 11's victory far easier. Piccolo also shows up to fight Broly as he's not completely outclassed like in the series and may even overpower him with Kaioken. Where things change significantly would be the Moro Arc with Piccolo being able to handle Saganbo easily and perhaps the group would be able to defeat Moro before Galu arrives.

 

[Ultimate Cell]

For the earthlings, it wouldn't change much going forward when Kaioken x20 would still be far from on par with the SSJs (and it's hard to say if they could develop beyond Galu's peak with it). With Piccolo, on the other hand, it may be an absolute game-changer if he utilises it right. With Namekian regeneration possibly being a way of mitigating the strain of Kaioken, he could potentially bring it to far greater levels than x20 at the cost of more Ki loss.
In any case, one of the lower levels of Kaioken would allow him to completely catch up to Gero when he attempted to flee and he kills him before he can get to the lab. Trunks then advises everyone to find Gero's lab and, once they do, they destroy it completely. Kaioken is enough for Piccolo to easily kill Cell after he gets his explanation before Cell can attempt the Taiyoken, so the Cell Arc's battles come to an abrupt end. Trunks then gets the plans from the underground lab and stays a while to train, Goku bringing up the Rosat which everyone eventually goes in at some point. Trunks then returns to his future.
I'll say that the training from the Rosat would've provided Galu there was some knowledge of a state beyond Super Saiyan as with him having confidence in the potential power of Gohan's rage, with he and Vegeta achieving SS2 during the timeskip. When the Boo Arc happens, either Goku, Vegeta or a Kaioken amped Piccolo quickly deals with Dabura and averts the entire battle with Boo.
The start of Super goes otherwise the same with Beerus not being pissed off enough to destroy Earth, yet still insistent on discovering the Super Saiyan God and starting a fight because of that. Kaioken x20 or higher may stop Piccolo being beaten around by Tagoma, though Freeza still kills him all the same. In the Universe 6 Arc, Piccolo's gains combined with Kaioken allow him to oneshot Frost, Magetta and Cabba before facing Hit, who even if winning, would be forced to use his full power and just get beaten by Vegeta anyway. Piccolo beats a sizeable amount of ToP contestants on his own and perhaps Tenshinhan would avoid being fodderised so quickly too, though it'd be only a matter of time for Ten and Piccolo would still be caught off-guard like he was in the series . Due to not being tutored by Vegeta, Cabba nor Caulifla would have SSJ, meaning both are eliminated long before Potara fusion with Kale becomes an option, making Universe 6 eliminated far quicker. Gohan not stalemating with Kefla allows him to help out a lot more against Jiren, making Universe 11's victory far easier. Piccolo also shows up to fight Broly as he's not completely outclassed like in the series and may even overpower him with Kaioken. Where things change significantly would be the Moro Arc with Piccolo being able to handle Saganbo easily and perhaps the group would be able to defeat Moro before Galu arrives.

So in this timeline Piccolo is acually relevant passed Cell Saga . Would the Goku Black sage still remain the same too?

 

[Captain Cadaver]

Probably considering there was limited space in the time machine and Piccolo's absence from the arc wasn't suggested to be from a lack of power, considering he had no metric as to be able to tell whether or not his Mafuba would work on Zamasu. It would likely remain unchanged as Vegeta and Galu would consider the Goku Black situation enough of a personal matter to forego leaving things to someone arguably more capable than them.