Damage is needed to 4 different tanks.
High RoF, accurate and high pen on a mobile platform is preferred. I used E50 with 88mm gun, but I would also strongly consider using arty as well.
Its very easy to switch targets once you have damaged a tank, and you can shoot at pretty much the whole map if you need to. Usually the stock guns have a faster aim time and RoF so they are the ones to use to get the maximum number of shots out.
Possibly a Type 4/5 with HE rounds would work but they can be caught out if you need other tanks.