By scale, do you mean in power levels? I couldn't answer that in confidence. But to your other question, yes, Gohan was the only one to achieve SS2 at the end of the Cell Saga. Well unless you want to count Cell as well, as he did have saiyan cells and came back roughly as strong as Gohan after he exploded.
Back to the scale question, basically the trick to going SS2 is increasing your strength without losing speed.