User blog comment:Xilinoc/Ch. 609 - "A"/@comment-25606271-20141211185605/@comment-5657895-20141212054817

Yamamoto is stronger than Ichibei. Ichibei's ink powers can't exactly work on a guy who evaporates all liquids within a mile radius.

Besides, being stronger than all 13 Squads was only said after Yamamoto died. Not to mention Yamamoto alone was probably stronger than almost the entire Gotei combined (excluding Shunsui, Unohana, and Ukitake).

Royal Guard seems like a pack of Shunsui or Unohana levelled fighters, so imagine 5 Unohanas. Pretty damn powerful.