Originally Posted by Vagrant Lustoid 2

No, that's why Vegito knows the Kamehameha and has the ability to blend it with the Big Bang. The evidence is right there. The Fusions obviously exhibit the memories of their previous forms, or else they wouldn't know anyone, so clearly they can remember how to do the techniques.

Anyway, I've always been iffy on Gotenks being able to reach SSJ3. From what I remember of the manga, I always assumed it was a Giji SSJ3, but that's a whole other can of worms that is entirely unrelated to this debate.