Although SSJ4 was not featured into Dragon Ball Z, it is possible to get this form of Vegeta, Goku and Gogeta (Goku and Vegeta fused by Fusion Dance). Unlock Goku, Vegeta and Veggetto at their strongest forms (Goku SSJ3, Vegeta Magin Vegeta and Veggetto SSJ). Then, complete the entire game including Trunks' Extra Story with only those three characters at their strongest form in any order.