What kinds of tests do the epf put everyone through? What kind of data are they collecting? Why were Sunita, Hueso, and Draxum the first of the yokai to be collected?
I guess the 'tests' actually double as purge attempts. The EPF pit one to five randomly selected mutants and yokai (each) against each other every day. They keep track of every single hit, especially the ones eventually intended to kill, in order to track how much those entered can take (think the Battle Nexus but for science). I had thoughts of a maze trial, one similar to Hueso's maze of death but way more trap and trigger heavy.
They're mainly collecting data on how to kill yokai, purge them from society and 'fix' mutants by demutating them or killing them.
Sunita and Hueso because the turtles had been with them when they were captured. It happened fast, one second they were leaving the restaurant and the next they were getting tossed into the back of an armored van. The EPF raided the place afterward, a struggle insued and then Sunita and Hueso were also in the van after helping the restaurant guests to escape. Draxum was one of the ones captured first because Mikey was the one that the EPF let escape. He originally went to April's home, but no one was there, so Draxum was the next best option. Plus, the sheepman could help him get his brothers out of the EPF's hands. Of course, it doesn't end well and now Draxum is captured along with them. Mikey feels extremely guilty afterward and spirals about it sometimes and being in solitude doesn't help.
Now I'm gonna take a second to add something extra:
When mutants or yokai are first taken, the very first thing the EPF does is determine which they are and ask about background info (name, age, family relations, etc). The second thing they do is determine what animal/mythological creature they are. Once they know, if that particular species has even the smallest chance of biting/being prone to frequent violent behavior, they are marked as so. Biters are marked with a brand of teeth and fighters are marked with a brand of a fist. Should either do those enough and they gain a collar, one that doubles as a shock collar and muzzle (totally not imaging Donnie screaming and writhing on the ground as I write that what are you talking about?). Should the mutant/yokai still do it regardless, they are placed into a dark room for a week alone. If in the case the individual still acts aggressively, then they're killed, no questions asked. Planning to have that nearly happen to Donnie and Raph, but story for the story
Continuing on the things about humans, April will never be put into the camps, BUT after the EPF advertises them in order to take an edge of the lingering fear of the unknown from the Krang invasion, she begins passively and passionately defending the mutants and yokai inside, especially because she knows that her brothers and best friend are in there because they hadn't ignored her messages this long before. She goes onto practically every forum website available and tries to get people on her side but it next to never works. Her mom has to watch her pour everything into it and eventually has had enough and decides to help in what little way she can. April's mom soon gets put into the camps.
Because Elara is a focus at the moment, she will also be added in. She too gets put into the camps, but only because she was also with the turtles when they got caught and tried to save one of them. But she doesn't get captured right then. She gets three days time to hide, the EPF coming after her once they have Draxum. During that attempt to hide, that she doesn't know is happening, she tells her mother and sister what she witnessed, unknowingly putting them in some danger because they too would defend mutants/yokai without question. They, however, are able to get away after Elara's caught and join forces with April in whatever invisible shadow she's been in.
Humans who cooperate with the EPF are able to visit one mutant or yokai of their choice for a small period whenever they'd like. Which Elara does, no matter how much she hates it. She chooses to see Donnie more often than not. At least until April is able to get into contact with her.