How do you pick up stuff in plazma burst 2

I don't know what you're talking about, but here is a special trick on plazma burst 2
campaign mode.

Kinetic Module: Aim the pointer (cursor) at any object, dead or dying enemy, or at an enemies weapon, and press and hold C. Move your cursor to the desired position, and it will kinetically move that object. *Only works in Single Player*

And if you meant a gun, like you have a defrilibrator and you want a grenade launcher, press v to let go of current gun, then go get the grenade launcher