I'm going to try and explain this.
We learned from this episode that Gohan is using Ultimate and Super Saiyan 2 again. He had not used these forms in DBS until Ep. 88 (BoG black-haired Gohan was his Base form). That means that during his fight in Super Saiyan against SS Goku, Gohan was near his Buu Saga Super Saiyan 1 powers.
If Super Saiyan 1 Gohan is approximately Super Saiyan 1 Goku, then their Bases should be the same. However, a Base Goku pushed a Beerus attack away during the end of Battle of Gods, as well as battled moderately okay against Monaka-Beerus.
Gohan absolutely was never above his Ultimate state when he fought Goku. This means Base Goku against Base Gohan MUST BE WEAK. Yet, how is it possible that Base Goku fights well against Beerus? THIS MUST RESULT IN A STRONG AND WEAK-LOOKING BASE.
So, here is my theory.
Also, if anyone says that some parts of DBS anime are not canon, please leave. We have been over this time and time and time again. I will be trying to find internal consistency.
Gohan has his Base form and his Ultimate transformation. This episode confirms that they are different things (his SS2 hair flickered into Ultimate, for god's sake). The confusion stems from the fact that they look too similar because of the black hair.
Gohan has two black-haired forms: Base and Ultimate. Goku should have two black-haired forms: Base and Super Saiyan God.
If Gohan's Base was not in Ultimate and he cannot stack Super Saiyan on top of Ultimate as people had thought ... then SS1 Gohan = SS1 Goku, as shown during the field fight where Chi-Chi yells at them. If their SS1 forms are equal and their Base forms are equal, then Goku's Base form and SS1 form cannot be as strong as it was during Battle of Gods ... unless ...
My belief is that when Goku went SSGod and had red hair he lost it, but it got absorbed into his Super Saiyan form for a bit and then transitioned into his Base form. The SSGod power was merging with Goku's being. During DBS Ep. 14 his Super Saiyan form was very powerful, but as I spoke about ... SS1 should have only been that powerful in that moment. My idea is that for a VERY BRIEF BIT the SSGod power was imbedded in Goku's Super Saiyan form. When he is fighting the sun ball attack from Beerus he turns into Base form and is able to stop it. This should be when the SSGod power was merging with his Base form. It hadn't merged with his Base form yet because he went into SS1 during the ritual.
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Our biggest issue has been whether Goku's power is incredibly strong now. With the recent episodes, we all seem to be in agreement that Goku's forms are all weaker than SSGod except for SSBlue. SS2 Goku and SS3 Goku during the Black arc make sense to be relatively around their Buu arc powers (how could Trunks get so strong to be above SSGod?). That leaves BoG Ep. 14 Super Saiyan and the weird instances of Goku's Base form being strong.
I think it makes sense to just say that the powerful SS1 at SSGod level was just the SSGod power being semi-merged with Goku. It only was fully merged after the sun ball attack. So Goku's Base would be relatively at Buu arc levels, and he now has Super Saiyan God but it looks and feels like a Base form. During DBS Ep. 14, Goku basically had Super Saiyan God, but it just looked and felt ki-wise like SS1. This idea works perfectly because he goes from SSGod to SS1 to Base and doesn't switch around among those. As seen in the graphic above and in the show, it is consistent. It makes sense to believe it was merging with him.
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So Goku used Base against Botamo and Frost. He used a black-haired SSG against Hit and Monaka-Beerus. This makes things consistent, as they are both above SSG tier. Goku also could be said to use black-haired SSG against RoF Frieza. He didn't feel like he was jumping from relative Buu arc Base to SSB, as Frieza compares black-haired Goku to stronger than Majin Buu. The intent behind the RoF arc was that Goku's Base was around SSG anyways. Black-haired SSG explains how a seemingly Base Goku fought evenly with Base Copy-Vegeta who crushed SS3 Gotenks, yet Base Goku is around Base Gohan who was not Ultimate. This could explain why a strengthened Slim Buu didn't instantly kill a relative Buu arc Base Goku. He could have used black-haired SSG. This also keeps consistency with the DBS manga where Goku and Vegeta have SSGod. In the manga they have Base, SS1, SS2/SS3, SSG, SSB. In the anime they have Base, SS1, SS2/SS3, black-haired SSG, SSB.
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