How about we call Pure-Evil Boo...

[Fantastische Hure]

Ikari no Boo or wrath Boo (or Boo of wrath).

He's not Boo's evil incarnate, just his anger incarnate. Vegeta thought he might give birth to another one because he might get that angry again.

Ikari no Boo sounds good.

 

[Void]

For some reason I vaguely remember some material somewhere referring to him as the Boo of Pure Wrath. Fuck if I can find it though.

 

[Ultimate Cell]

Just call him Negro Buu

 

[Fantastische Hure]

For some reason I vaguely remember some material somewhere referring to him as the Boo of Pure Wrath. Fuck if I can find it though.

That sounds good as-well.

 

[Captain Cadaver]

For some reason I vaguely remember some material somewhere referring to him as the Boo of Pure Wrath. Fuck if I can find it though.

That seems to just be a Viz thing, however, considering the anime refers to him as evil several times in Episode 255 such as Aku (evil/demonic) Boo or Piccolo calling him Jyaku no Boo (the evil Boo); not to mention Piccolo also referring to him as having an evil Ki.

 

[withheldforprivacy]

Nigga Buu.

 

[theallpowerfulpuipui]

Kid Buu

And by the way he was stronger than Buuhan