Here is the full list of all 18 Mech Anarchy achievements.
Complete Boot Camp
Kill an enemy who has your flag
Kill 1,000 Enemies
Infected 10 Players
Score a goal in soccer
Kill 15 Mechs while king of the hill
Dethrone the king of the hill
Dominate all three territories
Get 500 melee kills
Kill 3 players without dying
Kill 4 players without dying
Kill 5 players without dying
Kill 6 players without dying
Kill 7 players without dying
Kill 8 players without dying
Kill 9 players without dying
Kill 10 players without dying
Walk a marathon