DB Multiverse

About the choice of a Genkidama

Most of you would say that in the movie, Gokû was already doing a Genkidama, except it wasn't said. So I answer, yes and no.
In the film, it's a scene from Saint Seiya that's happening. We see weird auras (which we never saw and will never see again in Dragon Ball), Gokû takes them and suddenly becomes invincible. What the hell is that?
If Kulilin did the same thing, could he have pierced Broly with his fist too? If Gohan SSJ2 gave his energy to his father, Son Gokû could have beaten Cell?
So my idea was to replace it by a real Genkidama.
Plus, as it's the first time we take the entire energy of people and not just a part as usual, it could have given the idea to Vegeta, to do the same thing against Buu!

I'm told that in the film with the Cyborgs (DBZ movie number 7), Kulilin says that you have to be pure of heart to throw a Genkidama, and that a SSJ is not.
So first...
— Where did Kulilin get these informations?
— Precisely he says it in order to point out that in spite of these laws, SSJ Gokû managed to do it in the movie! He even absorbs it, to become invincible again...
So let's imagine it's true... here is my answer:
Gokû spent a year training to keep his SSJ state all the time, so he wouldn't be "excited" any more by this transformation. I believe that it's clear, since his journey in the Spirit Room, that Gokû is once again totally pure of heart in SSJ1. (see how his eyes are round again)

I also want to say that this chapter shows how happened the fight against Broly, as it is in the memories of our heroes of universe 18 ("our DBZ"). For me, for DBM, the real movie didn't happen, what happened, is this (it's more compatible with the rest).