I cant think of anyone outside db/z/gt who could beat goku slightly. only one in the dbz franchises who could beat goku alone is Yi Xing Long and the highest fuzed characters. No one else. Now you could argue and say that if goku were in character and refused to kill immediately and of course wouldn't toast the planet then a character like Aizen stands a 1/100 chance. But I've yet to answer the question. I cant think of anybody.