Please note that I've never gotten far into the Anime or Manga, this is from what I learned from a friend of mine who loves the show, with my own touch. As such, this list may not be entirely accurate. Enjoy
Plus: Pluses are simply Human spirits, they exist on a mostly Astral plain, and so are considered to be the weakest of all Humanoid formations. Don't underestimate Pluses TOO much, they can still interact with the Human World, however this takes energy, and the more energy they use, the faster their Chain of Fate will disappear.
Basic Hollow: Immediately after the Chain of Fate has vanished, the Pluses' form will "explode" and reform elsewhere as the Hollow, Hollows are estimated to begin with 5X the physical strength they had as Humans, the stronger in life, the stronger the Hollow once it's born.
Hollow Stages: Hollows can "evolve" into higher stages of their current forms by devouring souls, or even other Hollows. Devouring Hollows is the quickest way to evolve, so quick that most cannibalistic Hollows would move on to become stronger than that of The Grand Fisher. Though it's not certain, it can be assumed that Hollows do not indefinitely evolve, and may move on to a higher class after about 2-4 stages.
Menos: There are two stages of Menos, Gillian and Menos Grande. Gillians stand 20-60 feet tall, and are now capable of using the power Cero. Gillians are an amalgamation of several Hollows that had either begun eating themselves or simply got too close to one another. Menos Grande are the result of many Gillians absorbing one another, and are so powerful that one may have the destructive power of a 1KT Atomic bomb. Both forms are mostly without Personalities, which makes them even more dangerous and unpredictable. It's yet unknown if a Hollow can skip the stage of Menos and become and Adjucha simply by gaining enough power.
Adjucha: Adjucha are extraordinarily powerful beings, fully capable of wiping out cities if they so choose. Adjucha are vaguely Humanoid in appearance and retain the mask of the one who controls the amalgam. Not much else is to be said about these Hollows, except that they are NOT to be dealt with alone. Adjucha are rather interesting because of the displacement of the "Hole", this hole that appears in every Hollow isn't just limited to the chest anymore, it appears on any part of the body.
Vasto Lorde: Vasto Lordes are essentially the strongest form of Adjucha, and that's about it. These creatures are definitely more Humanoid than your basic Adjucha, but as many video games and scientific studies may tell us, size hardly always matters. If one were to encounter a Vasto Lorde, they may as well bring the entire Military forces with them.
Arrancar: When an Adjucha removes its mask, the creature finally gains a new, fully Humanoid shape. These creatues have Soul Reaper-like powers and can be comparable to Gods (on the Human Scale). The most powerful of these being the Espadas, Hollows with enough power to possibly end the existence of Humanity (See Barragan) though it would take some time, the capability is there.
I hope you enjoyed!
>End of Lesson