I dont know the complete list but here is what I atleast do know. Im not sure if the complete list has been achieved yet either way.
- Solider - 25 kills
- Assassin - 1 solo kill
- Combatant - 75k dmg
- Commando - 10 kills
- Quick Draw - 1 killing blow
- Shield - 5k Defended
- Guadian - 2k Defense 1 life
- Defender - 1k Defender points
- Paladin - 10k defense 1 life
- Demolisher - 2.5k+ single hit
- Annihilator - 5k+ single hit
- Healer - 75k Healing
- Medic - 2.5k+ single heal
- ??? - 5k+ single heal
There are also some for getting defender points but I cannot recall the amounts for them or their names.
I do know however that you cannot get duplicates for any of these, as ive personally healed 20+ games and i've done almost every heal at 2.5k+ and never got more than one medal for it.
Hope this helps, id love to see the full complete list aswell ! ... if anyone has any to add or update , comment and ill add it to the list here so we can have something for it in one place.