Pick any American Tank and kill any 4 enemy tanks in one match...
My recommendations if you have them are the Tier 5: M4 and Tier 6: M4A3E2 and M4A3E8. I really love the big guns on those, the 105mm. It can wreck enemy tanks in one shot very often!
Another good beginner option is the Tier 1, T1--you just need to rush the enemy and take out 4, which can happen once you know how to use the tank well. Do get the T1E5 M1933 package for the T1--it's extremely important for Tier 1 battles as it'll eliminate enemies in one go if you aim right!
I'm including a clip from the moment when I got the achievement while using my M4: