The outflanking russ battlecannon is a S8 ordinance gun. It can become a vanquisher, which trades the Large Blast for heavy 1 Armorbane at the same range and the same price. So yeah, it can deal with marine tanks. Beware invulns and cover saves.
The Kraken penetrators are also S8 armorbane, but on a more fragile platform and one-use each. They can be shot all at once though, so you can have 6 armorbane shots in the turn you come from reserves, as opposed to one per tank in the russ squad. Beware "Interceptor".
The artillery units are ordinance and barrage, which means they roll twice against the side armor (great against flare shields), so they can be used for anti-tank too.
Drop pod heavy marine armies are the greatest threat to your low rear AV vehicles and aegis defense line deployments.
Assuming the marines are coming in their fastest assault transport (any of the spiky pods), they need to wait at the very least until turn 2 in order to charge. The heat blast can hurt your infantry, but usually not your tanks.
It all depends on if you can land 2 of those high-strength pie plates on each drop pod: one to pop the pod open, the other to flatten what's inside.
Thanks for the answer. I guess that my question is more a mathammer one, since I find that the costs for those tanks are high and BS3 hurts. I understand part of the appeal of 30k is the fluff, which I also like. But I am surprised I haven't found as many mathhammer analysis for 30k.
I might do one with spartans vs militia tank orders.