Goku and Oob

[GSM123]

Goku told Vegeta he kept an eye on Oob and recognized him at the Budokai. Yet he didn’t know Oob had never trained and couldn’t use his power? What’s up with that?

 

[Hector]

He assumed he could use it as Buu's reincarnation.

 

[GSM123]

Goku literally says he’s been watching Oob.

Chapter: 518 (DBZ 324), P2.4-8
Context: Vegeta asks Goku why he’s entering the next Tenkaichi Budoukai
Goku: “Because someone’s entering who seems incredible! I’ve had my eye on him for awhile, and he came to the tournament grounds this morning.”
Vegeta: “What!? …I don’t feel any ki that strong…”
Goku: “He’s completely suppressing his ki now. ..But somehow I can tell…that he’s definitely strong…”
Vegeta: “…Hmph, are you joking? There’s no way a guy like that could exist…Don’t tell me he’s an alien!?”
Goku: “Nope, he’s an Earthling.”
Bulma: “Huh!? That’s impossible.”