From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Vegeta Jr.'s true heritage was never revealed, therefore it is unknown whether he was descended through Trunks Brief or Bra Brief. Toriyama simply stated in an interview in the Dragon Ball GT: Pāfekuto Fairu that Vegeta Jr. was a descendent of Vegeta and Bulma.
 Dragon Ball GT
Vegeta Jr. appeared in "Until We Meet Again". He was Son Goku Jr.'s opponent in the Tenkaichi Tournament. The results of their match was never revealed, but both were seen to have the ability to become Super Saiyans despite the claim that no one with less than a quarter-Saiyan heritage could achieve the form. Even though Vegeta Jr. was only seen for a moment in the series, his personality was reminiscent of his ancestor Vegeta (Vegeta Jr.'s reaction to Goku Jr.'s Super Saiyan transformation was reminiscent of Vegeta's reaction to the Multi-Form technique he witnessed during the Saiyan Saga when he said, "Hey, that's pretty cool"). He also strongly resembled Vegeta down to his upright standing hairstyle and widow's peak.
- Bukujutsu – Vegeta Jr. shows this ability in the Tenkaichi Tournament when he fights against Goku Jr.
- Ki Blast – Although he is not shown using this, there is no seeing why he does not know how to use it. This is because when Goku Jr. turns Super Saiyan in Dragon Ball GT: A Hero's Legacy, he immediately masters the technique and since Vegeta Jr. can also turn Super Saiyan, then there is no seeing that he cannot use it either.
 Super Saiyan
Vegeta Jr. used this form against Goku Jr. in the Tenkaichi Tournament. He appeared exactly the same as Vegeta did when he turned into a Super Saiyan, his hair not changing shape, but the color going blond and having a more pronounced aura, and his eyes turning blue-green.