Legends say that those who disagree with Goku being in Smash come to meet a horrible end. Nobody knows who is responsible, but the killer always leaves the numbers "578" near the crime scenes.
Also he lost to Superman TWICE but blind anime fans think their precious Goku is fucking Superman fused with 18 different gods from all religions and EASILY capable of beating a man that has just about infinite power. This is still less ridiculous than Superman fans.
Also Goku is apparently shit at parenting.