Board Thread:Questions and Answers/@comment-10797017-20130624101208/@comment-26420452-20130712191648

Urahara is a master of Kidō. During his fight against Aizen, he could've used Hadō #125 instead of going through the trouble of inventing 2 ad hoc Kidōs beforehand. Nevertheless, I don't exclude the possibility that Hyōsube might've invented other numbered Kidō while being in the Royal Guard.