A few new ideas i had for weapons in Tf2, alot of them team based.
The Oil Grenade - Pyro secondary - (liquid based throwable)
Coated enemies take an additional 50 damage upon ignition.
Enemies already on fire take only 30 damage upon being coated, and ignite any other non ignited enemies coated by the same grenade.
Teammates coated gain speed. (Same speed boost as disciplinary action, but lasts longer due to grenade having to recharge)
Syringemans Surplus - Medic primary - (syringe gun)
Upon hitting a teammate, it replenishes ammo.
Alt fire - toggles view of teammates ammo amounts (shown by a meter that indicates overall ammo amounts)
-50% fire speed
+50% velocity (less projectile drop)
????? - Scout secondary - (dart launcher)
A one shot recharging (slow recharge) dart shooter that shoots a sonar dart (or something like that) that temporarily allows your team to see enemy buildings health and ammo. Proximity based (only shows things that are close to where the dart landed/hit.
Rigid Roulette - Heavy Primary - (minigun)
On spin up, you are frozen in place but given a +50% damage resistance.
+25% primary ammo
-25% healing rate from healers while spun up.
(This last one was a friend's idea, i just tweaked it a bit)
???? - Pyro secondary - (Shotgun)
On hit - ammo is replenished (for primary as well as secondary)
looking at a teammate and hitting alt-fire replenishes their ammo at the cost of your own ammo.
-33% ammo (4 shots)
+15% reload rate.