The Battle formation the Project E.A.B[1] adopted is a three man crew where one will the take a supportive role while the other two will take the offensive role. Although a five man crew should be more suitable in fighting the beasts, the government and the field researchers find out that making more than three people to fight a beast will make the later gain an unusual innate power that doubles the combat standard of the beast which is nightmarish to the combatants. And so, without much debate among the higher-ups of Project E.A.B and the government, they adopted the three man crew.
And also, due to a strange mist that spread all across the unclaimed territories in the world, men and women that is 20 years and above will shockingly turn into zombies. After this discovery, the government had no choice but to let only teenagers to fight the Ferocious Beast in the unclaimed continents.
As for the Battle styles, after much bitter research both in field and in the lab. The scientist finally found a way for mere teenagers to fight these Beasts. This 'way' is a special weapon called 'Juggernaut Weapons'
The researchers and scientist created these Juggernaut Weapons by using pieces of the comet to create them. The researchers find out after weeks of research on the comet that it can grant both a living being and inanimate objects explosive power that is out of human imagination. But due to the weak constitution of humans, the explosive power could only be done on animals but the humans didn't mind since they could use this source to make more powerful weapons of there own.
But unfortunately for the humans, after making a few Juggernaut Weapons, they found out that these weapons can't randomly be picked but the weapon has to chose it's owner. Although this discovery annoyed the government and higher-ups of Project E.A.B to no end, they eventually had to comply if they have to fight the Ferocious Beast. But one thing they know is that the Juggernaut Weapons explosive power is more helpful to them than any Battle Arts In the world.
[1] An abbreviation for Project Eradicate All Beasts ( ꈍᴗꈍ)