Originally Posted by apocalypse1280

Goku's base form in GT is very powerful, almost equal to SSJ3 Goku in Z. Now having said that, to be honest, Vegeta has always been training, as seen in the lost episodes, before the Baby Saga, so I don't think he was too much behind Goku. In fact, when Vegeta was gonna fight Goku after the tournament, after Mr. Satan had beaten Majuub, thanks to Majin Buu, both Goku and Vegeta powered up to SSJ, which means that Goku knew his SSJ would be equal to, if not slightly more powerful then SSJ Vegeta. If Goku was more confident, as shown before hand, he would have just remained in his base form, which he didn't. So SSJ4 Goku and Vegeta aren't too far off in power as say Goten and Trunks when they fused, seeing as how Vegeta's PL was even with Goku's in order to fuse in the first place. Pretty simple actually.