Kefla stated SSB Goku had a long way to go.
Kefla isn't a valid source of information. She is depicted as an incredibly egotistical person that makes many claims and assumptions with no basis.
Goku using Kaioken while fatigued anyway, and even using Kaioken x20 against Jiren while even more fatigued.
Except the fight between Goku and Caulifa establishes that Saiyans somehow regain their stamina by fighting. Goku was less fatigued against Jiren than he was against Kefla.
Goku doesn't always say "times 20" even when using x20 Kaioken (he only said it once).
This isn't proof for, or against, Goku using times 20.
Kale was able to briefly swap hands with suppressed SSG Goku and got tens of times stronger with the Potara.
Caulifa is far weaker than Kale, meaning she wouldn't contribute as much to the fusion. To add further, Super Saiyan Blue is just Super Saiyan with God Ki, meaning Goku himself grew dozens of times stronger by going Blue. We also don't know the degree of how much of a boost Potara is, in the context of that fight (due to Vados claiming it's the sum multiplied by dozens of times).
You could argue that Base Kefla blitzed SSG Goku, but that's somewhat contradicted by SSG Goku taking direct attacks from Base Kefla, and dodging her. Which implies the gap isn't nearly as large as that singular scene showed.
Goku Blue then took on SS Kefla directly, even trading blows evenly with her at times.
Let's add a low-ball and high-ball estimate for their comparison:
SS2 Caulifa = 1 (Therefore SS = 0.5 on the basis that SS = 50x and SS2 is at least 100x)
SS Kale = 10
Caulifa + Kale = 10.5
10.5 * 20 (Low-ball Fusion) = 210
10.5 * 90 (High-ball Fusion) = 945
Therefore: SS Kefla = 210-945
SSG Goku = 10
SSB Goku = 500 (10 x 50)
X2 SSB Goku = 1,000 (10 x 50 x 2)
Therefore: X2 SSB Goku > SS Kefla >> SSG Goku
You can argue the semantics of how different in power Caulifa and Kale actually are, but the point depicted here is that the gap between Kefla and Goku Blue isn't nearly as large as claimed.
Kefla's rapid growth ability.
Which Goku also depicts against Caulifa and Kale, with Whis even noting Goku was rapidly adapting. You also can't claim how much Kefla was growing against SSB Goku to claim Goku went X20.
Kefla and Goku power up even further after he punches her while being amped by Kaioken.
If we assume this is 'Kefla's growth' then what would that imply for Kaio-Ken Goku? Simple, it proves he wasn't using X20 at the start and there is still no evidence that he used X20 even after powering up. To add further, he could have just been powering up Blue further or even regaining stamina.
There are too many factors here to make such a claim.
Kefla saying she's far from
That has no bearing on what Kaio-Ken level Goku is using.
Kefla one shotting Kaioken amped Goku after getting one shot her self.
She wasn't 'one shot' at any point in the battle. At most, she was knocked away with her arms steaming. To add further, Kefla one-shotting Goku proves nothing in regards to Goku's Kaio-Ken.
Kefla activating UIO2.
Again, no bearing on what level of Kaio-Ken Goku is using. We have established that Goku grew much stronger with each -Sign- and, to add further, Kefla only had to rival the Spirit Bomb to trigger it.
Kefla says she wanted a longer fight, after kicking Goku, implying she was holding back.
Again, zero evidence that Goku is using X20.
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In reality, the points are:
Evidence for x2
- Regular SSB Goku initially did well against SSJ Kefla.
- Goku was fatigued therefore couldn't use x20 Kaioken.
- Vados was unsure SSB Goku would be beat by Kefla.
Evidence for x20
- Kefla and Goku power up even further after he punches her while being amped by Kaioken.