Quote Originally Posted by JJ
Kwatts, everything is всё. Everybody is все.
But written "все" could mean either "все" or "всё"

Quote Originally Posted by ryzhevolosaja
I know the word "protiv," but in that famous famous film Battleship Potjomkin, a caption is "Все на одного... Один на всех," so I thought maybe "на" could also be used to mean "against" in other contexts, as in one thing to or on another in English, man to man, one on one, etc. Does it maybe only work in that context?
Yes, in fighting, military etc. contexts "на" can mean "against".
For example:

All against one, that's unfair.
Все на одного - так не честно (or maybe нечестно, I'm not sure if it should be together or separately)

Let's fight one on one, man to man, only you and me.
Давай драться один на один, как мужчина с мужчиной, только ты и я.