[SSJKarma]

now i know that you're gonna say something about this and i know you're gonna say something has:"it wasn't in the manga !" but i'll say it anyway...

yes they can control their SSJ form, but their anger is very uprising their heart isn't pure anymore, they fight to stay themself. why ?

reason: when goku tranformed for the first time. MASTER ROSHI sensed the energy and said that if goku wasn't able to control that energy, he wouldn't be himself anymore ! that's exactly what he has done. he was so angered that while fighting freeza he let him go into his 100% power form. mistake he made has freeza was his equal by then. but goku's anger made him SSJ form last forever !

second example...
when gohan got to SSJ2, he did the very same mistake has GOKU did with freeza, and he lost his father cause of that ! and piccolo said it himself... HIS ANGER OVERRIDE HIS JUDGEMENT !

even thou you'll say that it has nothing to do with DBZ... krillin even said it to goku while fighting SUPER 13, QUOTE:"you cannot do a genki dama with an UNCLEAR heart" UNQUOTE he said this while he was seeing goku get to SSJ when doing the genki dama ! the genki dama was very unstable when he got there, but goku somehow absorbed the energy and used it in a single punch !

now, i doubt he could have made a GENKI DAMA has an SSJ3.