This can't be a serious topic of discussion, SSB Goku could eradicate Buu whilst massively suppressed at an
infinitesimal portion of his power.
Let's look at the facts and compare and contrast these two characters.
Goku: multiple statements from Goku and Vegeta as well as the formers performance against Kid Buu indicate that SSJ3 Goku Buu arc could defeat Kid Buu whilst at full power.
-The narrator states that Goku in his SSJ form during his fight with Beerus was greater or at the least equal to his SSG form.
-Whilst suppressed in his SSG form Goku was throwing universal bunches ready to annihilate(ad verbatim) the universe.
-Goku expanded upon this power and mutated into SSB, a form which has been stated to exceed the power of SSG multiple times over.
-Copy Vegeta in base two shotted SSJ3 Gotenks, to scale properly lets elaborate on Gotenks power.
Prior to Goku returning to the other world he appraised Goten and Trunks power as SSJ's and concluded that they could defeat Fat Buu, Fat Buu proved himself as slightly below SSJ3 Goku, to be clear this is not Mr Buu which lost to Kid Buu, this is Fat Buu prior to becoming Super Buu.
Goku was only aware of their ability to become SSJ, so we can deduce that Pre Rosat SSJ Gotenks=SSJ3 Goku give or take.
Goten and Trunks then enter the ROSAT and come out with Piccolo asserting that in base they had surpassed their previous SSJ state in power.
So lets be generous and state that SSJ Post Rosat Gotenks=SSJ3 Goku(a massive lowball), and then Gotenks Stacks SSJ3 and becomes 8xSSJ3 Goku, meaning 8x Kid Buu given SSJ3 Goku is stated equal to Kid Buu. Vegeta STOMPED SSJ3 Gotenks while in Base...
-That Copy Vegeta is currently at least 10x weaker than current base Goku and Vegeta given during that time they were equal, and Goku faced Hit at Kaiokenx10, after the Goku Black arc Goku could beat Hit which was equal to SSB Kaiokenx10 goku during the U6 arc,whilst solely in SSB.
-Goku and Vegeta can stack SSJ on their new bases and the multipliers apply, so we can have SSJ3 God essence Goku which is 4000x base Copy Vegeta which two shotted a being 8xKid Buu minimum. SSB Is a completely different league of power than the SSJ/SSG transformations.
Kid Buu
-Kid Buu fought evenly with SSJ3 Goku, SSJ3 Goku after appraising Buu's power was confident at full power he could wipe out Kid Buu.
-Kid Buu is inferior in power to Super Buu,Buutenks,Buuhan.
-Super Buu was equivalent to SSJ3 Gotenks, a being multiple times stronger than Buu arc SSJ3 Goku. Goku was pissing himself at the prospect of fighting Super Buu with no absorptions and insisted Vegeta fused with him, whilst Goku was confident he could not only fight but defeat Kid Buu.
-Even when Buutenks devolved into Buu-Piccolo, Goku stated that Gohan could take him now.
-Using Gotenks scaling we have Buutenks as 2xSSJ3 Gotenks, as Buutenks Buu stated he was the strongest Majin, whilst being aware of Kid Buu given his fear of vegeta ripping Mr Buu out.
Buuhan=Super Buu with Piccolo,Goten and Trunks absorbed+Mystic Gohan, Mystic Gohan utterly demolished Super Buu which is=SSJ3 Gotenks with no difficulty.
-This Buuhan was trashed by SSJ Vegito, Vegito is stated to Be GokuxVegeta and stronger than SSJ3 Goku in base.
so Base Vegito=SSJ3 Goku and this Vegito can go SSJ, so at minimum SSJ Vegito was 50x SSJ3 Goku
-Goku in BOG stated that a stronger Vegito(given Goku and Vegeta were more powerful than in the Buu arc) stood no chance against massively suppressed Beerus. Yet SSG Goku could swap hands with Beerus at a much higher percentage of his power. So SSG>Buu arc Super Vegito
-SSG took Goku from multi solar system buster to Universal+, now this SSB Goku is astronomically stronger than BOG SSG Goku.
Vegito also proved there was a limit to regeneration, and proved it by almost eradicating a Buu multitudes of time stronger than Kid Buu.
So the no limits fallacy of Kid Buu endlessly regenerating is debunked right there.
The power difference is unreal.
Perspective: using those low balls, SSG>Super vegito, Base Vegito=SSJ3 Goku, Super Vegito=50xSSJ3 Goku=20,000xBase Goku.
Lets say SSG=20,000xbase(fucking lol) multiply thatx10 for Goku's power increase post Black arc=200,000, now stack SSJ transformations SSJ=10,000,000x base Goku Buu arc, SSJ2=20,000,000 Buu arc Goku, SSJ3=80,000,000x base Goku buu arc.
And SSB is even stronger than that, all the while the numbers are super lowballs..
You think He'd need a spirit bomb for fucking fodder like Kid Buu?....