User blog comment:Zwann/Vasto Lordes in the Espada, let's analyze./@comment-1659217-20091118013728

Aizen only recruded those who 1. made a pact with him - those are Barragan, Starrk, Ulqiuorra. Niell (probable). 2. those that he could control/intimiate. Grimjow, Yammi, Nroitra (I think he gained some of Niell´s riestsu after attacting her and thus got to nr. 5 from 8). 3. Aizen did NOT know of Ulquiorra 2nd release. 4. Aizen took the 3 strongest (in his estimation) with him and was very fustrated when they were shown not to be strong enough to defeat 5 or 6 captains (including some of the strongest) all by themselvs without any help from him, Gin or Tousen. = the four strongest were Vasto Lordes or quite close - Niell and Tia included - Wonderwiss must also be. I thjink that Ulquiorra was already a natural Arrancar; Barragan, Starrk, Tia and Grimjow all had fraction that were Adjudhas. Grimjow and his fraction were the first to be made arrancar by Aizan. If they found stronger Vasto Lordes in HM those hollows did not fill Aizen´s recurements: being controlable or willing to make a pact with him. As far as I can see, Barragan, Starrk,Tia, and Ulquiorra are still humanoid after resurrection. So is Grimjow. THat Ulquirra has a second release do I take as a hint that he was a natural arrancar when he met Aizen. He can be a Vasto Lord or so perfect a arrancar that Aizen belived him to be a vasto lorde.