Verified answer

Start:

Episode 264: Battle for the Universe Begins

End:

Episode 271: Spirit Bomb Triumphant

Goku Vs Buu

Goku Vs Kid Buu

Episode 264: Battle for the Universe Begins

Episode 265: Vegeta's Respect

Episode 266: One Minute Desparation

Episode 267: Old Buu Emerges

Episode 271: Spirit Bomb Triumphant

Kid Buu is the mother of all villians.

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Umm it's right near the end of dragonball z, in the Kid Buu saga. I think it's about the 6th or 7th to last episode. EDIT: I went and found it, it's in the 5th episode of the kid buu saga. The episode is called Vegeta's Respect