there are applications open to join the U.M.P, the requirements will be in the comments

Requirements to join:
1. You must be a well known being in the multiverse
2. You must have an empire with at least 100 galaxies claimed and at least 100 billion population
3. Your empire must be strong enough to help your allies incase of an attack

Here are a couple of empires that meet the requirements but haven't joined yet:
Inklings (Inkverse)
The Triangles (Shapeverse)
Diamond Empire (Shapeverse)
The Trapezoids (Shapeverse)
Squares Empire (Shapeverse)
Circles Empire (Shapeverse)
the rest have not been investigated

Shadearians

ok, a couple of questions:
do the "Shadearians" have 100 galaxies claimed and 100 billion population? (that would mean around 1 billion per galaxy which is a small amount if you think about it)
the Shadearians are pretty well known i will assume mainly from Shadronia though.
and is the army and Shadronia powerful enough to help the other empires in the team?

Well you see
They don’t like conquering so they just have a pretty big planet and artificial planets nearby

The Monarchy woukd gladly join

ok, is inkmatas the leader of the inklings or is it someone else

The Monarchy is the leader of the Inklings

alright, the inklings is now part of U.M.P (United Multiversial Powers if you didn't know)

are* not is

The Monarchy is a bit... Arrogant

The Pixels, they have claimed 99 galaxies and are in the process of claiming their 100th, but only have 99,999,999,485 population. They're the empire of the Pixelverse, and are led by a non-Pixel, being Gamer.

They almost meet the requirements, we will let the pixels join U.M.P once they get 100 billion population, and have a strong military

Oklol
also they have a select military consisting of Pixelite users, making Pixer not the only Pixelite user.