SCP Foundation

Specifics

The containment zone is to be expanded as needed to accommodate for all growth and expansion of SCP-XXXX. The containment zone is to be kept free of all wildlife.

Is there a reason the Foundation wants to keep increasing the number of contained instances? As opposed to containing a set sample, and simply destroying any further instances encountered outside of containment? Also, perhaps describe what wildlife exclusion measures are in use (fencing, bird nets, noise deterrents)?

Instances of SCP-XXXX-1 are 1 cubic meter kingdoms that appear to be made of clay and/or plastic.

'Kingdom', I think, basically refers to everything under the rule of a king/queen. 'Castle' would more clearly indicate that specific type of structure. Also 'appear to be …' Can the Foundation not do some kind of test to identify the material?

SCP-XXXX-1 are found on store shelves in a glass tank.

Glass is heavy and fragile and not very efficient packaging for something that doesn't require it.

The culture of SCP-XXXX-2 consists of a basic monarchy. SCP-XXXX-2 will follow a ruling individual from their original instance of SCP-XXXX-1.

I believe a monarchy would have a single head of state. This sounds more like perhaps some form of feudal tribalism (?)

SCP-XXXX-2B are more intelligent than SCP-XXXX-2, possessing the basic knowledge of a 25 year old adult human.

This comparison is not effective. Like, a 25 year old university-educated doctor? A 25 year old illiterate dirt farmer? I thought there was some sort of guide/essay on the matter (which I can't find just now), but this forum thread may be helpful for how best to describe the skip's assessed intelligence.

Overall

Firstly I must say, that looks to be an impressive amount of work put into the building of the language and whatnot. Though I must also admit that a lot of it is over my head, so I can't definitively say how much it adds to the article.

I might suggest changing the order of the information given in the article, so it begins with the basics (general description, appearance, origins/discovery) and then work towards describing the finer details (advanced physiology, society structure, language). So the pace and progression will keep readers interested without getting ahead of itself or moments of 'information overload'.

Also, when it comes to describing the general structure and specific traits of their society, I might suggest some research into the general practice of anthropology. This should enable you to more effectively categorize the different aspects of the skip's culture, and maybe to use more terms that will add to the feel of authenticity.

accomodate for all

should either be "account for" or "accomodate"

away from any other instances of SCP-XXXX-1 or SCP-XXXX itself

You said that XXXX only refers to the collective, which makes this line confusing. In fact, you could consider calling the things in the boxes SCP-XXXX and the little people SCP-XXXX-1 and SCP-XXXX-2.

1 cubic meter kingdoms that appear to be made of clay and/or plastic

This isn't very descriptive. What does a 'kingdom' physically look like? Is it like a castle, a little walled city, or what? Also, you never actually mention anything in the containment procedures about intercepting these things from the stores or covering them up.

SCP-XXXX-2 are 2.5 centimeter tall humanoids. They do not wear clothes and the pigmentation of their skin is leaf green.

Could probably restructure this a little. "SCP-XXXX-2 are naked humanoid creatures measuring approximately 2.5 centimeters in height, with green pigmentation."

SCP-XXXX-2 are sapient and possess a unique language and culture, all of which are consistent in each instance of SCP-XXXX-1

Are you saying that each -1 has a different culture, or that they all share the same one?

appear to "grow" from the ground, similar to a plant.

Remove the quotes from "grow" and change the end to "in a manner similar to that of a plant." Where do these seeds come from, anyway?

SCP-XXXX-2's leaf green

Leaves come in a lot of colors. That's not very clinical, so you can just say green.

SCP-XXXX-2B will write messages on anything they can and “pray”

Again with the quotes. "…on anything they can, and often perform actions resembling prayer". You may want to specify a bit more clearly what they're doing; there are a lot of different ways to pray.

joins a group SCP-XXXX-2B for the first time

Missing an 'of' after group.

What if the 'initiated' 2B refuses to eat the 2? What happens?

Out of what? Dirt? Iron? Steel? Carbon nanotubes? Neutronium? Can you try to be more specific? Furthermore, where are they getting these materials from?

Added 03/██/2017: The nisugo will also build traps to kill others.

Kill what ''others''? Also, the question about resources from earlier still applies here.

Incident Log - 03/██/2017: All contained SCP-XXXX-2, including new additions to containment, have reached containment zone boundaries. All 150 instances of SCP-XXXX-1 have become agitated, the usual caste system has been abandoned completely, and SCP-XXXX-1 have become extremely violent towards one another, regardless of origin. 33 deaths have been recorded so far.

Only 33? If these were humans, I'd understand, but these are small, fragile, creatures that reproduce like flies. The death toll would logically be larger.