How Buu's absorption works.

[withheldforprivacy]

All absorptions are additive unless stated otherwise. South Kai was evenly matched with Kid Buu, which is why Buu resorted to absorption. That was a normal additive boost. Because Dai Kai was not warrior class and his nature was meek, that absorption was substractive; Buu's power was reduced by an amount equal to Dai Kai's power.
Fat Buu's power was equal to Super Buu's, but he couldn't draw it out so easily because of his sweet nature. He accessed it all only right before he was split. Good Buu took all the good in Fat Buu (Dai Kai + South Kai's good) and Grey Buu took all the evil (Kid Buu + South Kai's evil). When, later, the total Super Buu's power was redistributed, Kid Buu was left with his ancient, original power and South Kai's evil side went to the other side, so Good Buu turned into Mister Buu (same appearance, a little different power), which is why the fatso that fought Kid Buu fared better than the one who had fought Grey Buu.

And now the gaps...

ANCIENT PAST

Kid Buu: 150

South Kai: 150 (140 of those units are his good side, 10 units are his evil side)

Dai Kai: 30

Buffed Buu: 300 (Kid Buu + South Kai)

Fat Buu: 270 (Buffed Buu - Dai Kai)


BUU SAGA

SSJ2 Goku: 100

SSJ3 Goku: 150

Fat Buu: 90
-1st power up (Dabura): 120
-2nd power up (Vegeta): 150
-max: 270

Good Buu: 110 (South Kai's good - Dai Kai)

Evil Buu: 160 (Kid Buu + South Kai's evil)

Super Buu: 270

Gotenks: 128
-SSJ: 160

Gotenks post: 180
-SSJ: 225
-SSJ3: 300

Kid Buu: 150

Mister Buu: 120 (South Kai - Dai Kai)

 

[Fantastische Hure]

So the Boo now is basically South-Kai?

 

[withheldforprivacy]

So the Boo now is basically South-Kai?

No. He has both Kais in him.

 

[Fantastische Hure]

I see now, I think.

Kind-of complicated but interesting.

 

[Let's Go Fearless!]

I think South Kai already died with Super Boo and only Dai Kaioshin is left which is basically Mr. Boo. Let's see what Super has to say about this.

 

[GSM123]

What says it's even additive in the first place?

 

[Fantastische Hure]

At-least Super-Boo said he added Gotenks power to his own, IIRC.

 

[Let's Go Fearless!]

What says it's even additive in the first place?

Chapter: 499 (DBZ 305), P6.1
Boo: “…If I just add that squirt’s power and…that ‘Piccolo’ guy’s brains, then…”

 

[Tapion]

My view on the whole Boo absorption issue is the following:

The Core People's energies don't mash well with that of Boo's. Boo's ki is demonic, pure evil, while that of the Kaioshin is mixed, with Dai Kaioshin's in special being pure innocence. Hence, adding their energy to his own has wildly varying effects - it could increase Boo's power with normal addition, lower it, or multiply it many times over.

When Pure Boo took on South Kaioshin, he found the first person who could ever match him and actually put him between a rock and a hard place. Hence his decision to test his absorption technique. By a stroke of luck, South Kaioshin ended up having an extremely positive effect on Boo's ki, multiplying it many times over.

---Pure Boo: 250,000

---South Kaioshin: 270,000

---South Boo: 2,500,000

South Boo gets sliced apart by Dai Kaioshin's durability ignoring flame breath, leading to him regarding Dai Kaioshin as a threat - to some extent, and absorbing him. But the wildly varying effect of mixing their kis ends up having the exact opposite effect as South Kaioshin did, lowering his current power many times over. However, South Kaioshin's positive influence is still hidden deep, deep inside Fat Boo.

---Fat Boo: 225,000

Finally, Fat Boo splits himself into Good Boo and Pure Evil Boo, and the latter ends up receiving most of their power with him. Pure Evil Boo eats Good Boo, and due to the fact that the original, pure evil-type of ki is now dominant again inside Boo's mind, Super Boo regains access to South Kaioshin's influence and receives an enormous power-up. However, due to Good Boo wielding a small sliver of influence in his actions, Super Boo does not regain access to all of South Kaioshin's influence, but merely the vast majority of it.

---Super Boo: 2,250,000

Gotenks and Gohan's kis are both influenced by their status as Super Saiyans, who tend to have vicious ki, therefore they influence Boo's power positively and only affect his personality to a small extent.

---Super Gotenks 3: 2,250,000

---Ultimate Gohan: 3,200,000

---Gotenks Boo: 4,500,000

---Gohan Boo: 5,450,000

Finally, Goku and Vegeta rip off Gohan and Gotenks's pods, leading to Boo reverting back to his baseline Super Boo state. Vegeta then rips off Good Boo. The massive shock starts Boo's infamous and debated reversal process. Due to losing Good Boo's slight influence but with the latter still being inside him, Super Boo temporarily turns into the fully-fledged South Boo with all his proper power.

However, all of his influence is at last removed, leading to him reverting back to the original Pure Boo, who then spits out Good Boo.

Good Boo possesses all of South Kaioshin and Dai Kaioshin's kis, but with the latter's influence weighing them down somewhat. Due to the complete lack of pure evil ki, Good Boo at his most angry should have the normal combined power of Dai Kaioshin and South Kaioshin.

 

[Fantastische Hure]

Gotenks was a SSJ(3).

 

[GSM123]

What says it's even additive in the first place?

Chapter: 499 (DBZ 305), P6.1
Boo: “…If I just add that squirt’s power and…that ‘Piccolo’ guy’s brains, then…”

Could be "add" in the sense that he's gonna have it, not that he's mathematically adding Gotenks + Him, though. Not that I disagree, but does anything contradicts saying it's not addition?

 

[SSJ2]

But even saying "I will have that squirt's power" implies a simple addition imo. He wouldnt single out Gotenks's exact power of it was going to anything else but add the sum of their powers together. I think it would look more like, "I can gain power from absorbing that squirt", if the quote was meant to be more vague. The word add has only 1 meaning in this case O think.

 

[ahill1]

I interpret the whole absorptions shenanigans the exactly same way as Tapion.