It's already been confirmed that the 5 being equal in power was an incorrect translation. Toyotaro says "I wanted to show the balance of power between the 5 of them".. Meaning goku/vegeta > gohan > broly/piccolo.. That still doesn't make 100% sense because there's no way that Piccolo is anywhere close to Broly, but it makes more sense than the "original" quote. Goku/vegeta > gohan >= broly >> piccolo makes the most sense based on feats, training, writing and common sense.
