Originally Posted by SRP76

"Keeping the Super Saiyan 3 form" means nothing. When he was in it, Baby manhandled him with utter ease (before Baby even powered up to his final form). Super Saiyan 3 Goku's attacks didn't hurt him in the least, and Baby slapped him around with impunity.

And Goku "held the form" as long as he wanted to in the second encounter, and Baby stated that Goku was no stronger than he was the first time. He then beat Goku with no effort again.

All this while being in, at best, Super Saiyan 2 from (Vegeta cannot go Super Saiyan 3). Even being a transformation behind Goku, Baby-Vegeta is far more powerful. In the same form, the power gap would be even wider. Goku would have no chance.