Ok so I have a question about the Haloball gametype. Is there a way to make it so that there is a weapon that when you pick it up and shoot it at a certain object, the object disappears, but then when you shoot another object of the same type, it disappears and the first object respawns?
No. If you set up a gun to be the goal, only the gun itself is the goal. The projectiles it fires are in no way associated with the goal label on the gun. What you could try is making the shape of the goal long and thin (that's what she said) because you could essentially create a 'goal lazer pointer'