when he is mad,sad or really hurt
Gogeta, the fusion of super saiyan 4 Goku and Vegeta.
after goku summon shenron
Majin Goku
No, he can't
yes
No.
Yes, Goku turned into a super saiyan 4 when he was fighting Baby Vegeta in Dragoball GT
When Krillin was exploded by Frieza, Goku became angry and he went Super Saiyan.
There is no such thing as a super saiyan 5.
Episode 230 "Super Saiyan 3"
Goku does not turn super saiyan 6 or 5 in fact. and it only goes up to super saiyan 3 in the manga and super saiyan 4 in the cartoon.
in Dragon ball AF he turn in to super saiyan 5