[RedCounty]

For some reason the person being shot at isn't losing any health or armour upon them being shot at, nor is weapon damage to vehicles doing anything.

There is nothing under the following:

OnPlayerTakeDamage
OnPlayerGiveDamage
OnPlayerWeaponShot

As I have commented them out. What could be the issue?

[Pottus]

All the players are on the same team other than team 0 look into that.

[Threshold]

As mentioned above by Pottus, this is your error.

This information is referenced on the SA-MP wiki.

Quote:

Originally Posted by SA-MP Wiki Players can not damage/kill players on the same team unless they use a knife to slit their throat. As of SA-MP 0.3x, players are also unable to damage vehicles driven by a player from the same team. This can be enabled with EnableVehicleFriendlyFire.

References:
https://sampwiki.blast.hk/wiki/EnableVehicleFriendlyFire
https://sampwiki.blast.hk/wiki/SetPlayerTeam