Board Thread:General Discussion/@comment-28503619-20160520045652/@comment-27544763-20160521093241

Number 4 and 3 are Vasto Lorde but 2 and 1 is not? No one said that all Vasto Lorde have sealed mouths. All hollows have different characteristics, and Harribel and Ulquiorra just happens to have similarities. In fact there was no picture of Harribel as a Vasto Lorde in the manga. Plus you can see the true definition of Vasto Lorde below:

'''Vasto Lorde (最上大虚 (ヴァストローデ), vasuto rōde; Japanese for "Highest Great Hollow") are the third classification of Menos and the highest level of evolution. They are extremely small Hollows, roughly the same size as humans, and are extremely rare in number. It is said that their entire number within Hueco Mundo can be counted with the fingers on one's hands. The combat capabilities of a Vasto Lorde are above those of the captains of the Gotei 13'''

The point is, considering that both Barragan and Starrk are human size, they are pretty much Vasto Lorde. Also, both Barragan and Starrk's abilities are above Gotei 13 Captains, as we've seen in the fight. They were dealing with not only 1 captain and mostly having no difficulties most of their fight.

With regards to Yammy, I think he is just an Ajuchas because he's not even human sized at sealed state and he was originally number 10. Plus it actually took a month of healing, eating, sleeping to store up his power + release his sword and get pissed at his enemies, to finally become the 0 espada. Yammy has too many conditions. All of number 4-1 Espada doesn't even need that much of preparation just to go full power.

Also I don't remember if there was a confirmation that there are Vasto Lorde in the book. But the wiki says Harribel is one of them (probably because of her anime flashback). But if we look at the definition of a Vasto Lorde, I think it's clear that 4-1 pretty much fit in the category.