Here is the full list of all 14 Teamkill achievements.
Hit an enemy!
Learn how to get off the ground
Wipe out a team from the match entirely
Hit multiple enemies with one shot
In Teamkill mode, hit an enemy who's on your starting team.
Be in the same match with someone involved in Teamkill's development!
Win a match without taking a single step. Looking around is fine, though.
Achieve the highest possible killstreak in a match
In Teamkill mode, be part of every team at least once.
*sips* ...yep, DOOM was a good game. (Play a match with centered viewmodel, using only your keyboard)
In Teamkill mode, eliminate your starting team. If you can't have it, nobody will!
Look, I know it's called "Teamkill", but..