goku does have the tail thing. although he doesn't have a tail anymore, any any saiyan worth his golden hair would have trained to remove the weakness, it might be related to a cluster of nerves that for some reason, take precedence over other feelings.
maybe batman can create a sonic device that targets that cluster and gets the same effect.

other weaknesses? Goku's somewhat human, so he needs to eat (a lot), sleep (plenty) and gets tired during fights. he (and vegeta) could hardly fight five minutes against kid buu at their outmost power, so even with an escalating battle (as shown in the video), I doubt goku could fight more than two to three hours (considering he and vegeta said that the thirty minutes they were to be allowed in the tournament is just going to be warmup).

Goku's only advantage is that he has higher energy output (kamehameha wave), relatively. I mean: superman's' fists are stronger than his eyebeams. Goku's wave is stronger than his fists.