With light tanks and perked heavy tanks something like the Tiger might be invincible to them. Then the Amreican light tanks(M3 Stuart as an example), British ligh tanks (Crusader as an example), German light tanks (Panzer III as an example), Italian light tanks, and Japanese light tanks could get a purpose in the game with perked heavy tanks. (Besides cannon fodder. Don't know many Italian or Japanese light tanks, sorry.)