User blog comment:Kartik "k2"/Comparision between regular shinigami/Hollow and Vizards/Arrancars/@comment-24165551-20140918174003

Is it that Vasto Lordes are as powerful as captains, or Vasto Lorde Arrancars? I think Hitsugaya said if Aizen made 10 Vasto Lordes into Arrancars they could take out the captains - but I don't think there even were that many Vasto Lordes. Harribel is the only confirmed one, though I assume Barrigan and Starrk were also Vasto Lordes. Ulquiorra may have been one as well. Not sure about Noitra, but if I had to guess I'd say he was an Adjuchas.

Ulquiorra was killed by Zangestu, who was way more powerful than the average captain. Barrigan was killed by his own power. Starrk fought two captains. Only Harribel was actually defeated by just one captain, and that's because Hitsugaya's Zanpakuto was a perfect counter to her abilities.

As for Visored being more powerful than normal captains, that's not necessarily true. They have to put there masks on for that to happen. Rojuro and Kensei were both defeated without their masks. Granted, it was really stupid of them not to put their masks on immediately, but that's beside the point.