The way to get another chasis is to reduce the health of an oponent to zero, after that their health resets to 5 and you can use that body for yourself. I tried to signify it with the change in the accent color but I guess I didn't make it all that clear, my bad.
Not really, I feel it is my fault for not teaching the swapping properly on a safe enviorenment for the player. I could have made that mechanic clearer.