An overheat meter would be better than ammo.
And tying the ammo to collecting balls would make your ammo limited, what if your team has every single ball in their side? Your team suddenly can’t get ammo unless you literally let the enemy steal from you or you purposely die to respawn with ammo.
And for health a regenerative health bar for not being in combat for [X amount of seconds] would be better, that would consist of not firing and not taking damage before your health starts to regenerate after a set amount of time.
As said already powerups are planned, so it’s not everyone using the same kind of attack for the entire match.
With the old [and still not released] dog and cat fort, the addition of powerups could enforce teamplay and defense a whole lot more. As offensive powerups could easily wipe through a fort and begin stealing with ease if a couple or few players don’t hold back to man the fort while others infiltrate or collect. As I can imagine some powerups will create minor subclasses like a temporary cloak, higher collection cap, infinite weapon cooldown, etc. Just a few ideas.