If we're talking about the late game (5-6 months), there's really nothing to discuss; the Orcs dominate everyone and everything (I tested it against all races, tried using various tricky features – it's useless; the Orcs have a bugged specialization, and Blood Fury is almost impossible to remove even with damage in the tens of thousands of HP). There was only a chance for the High Elves when using Arrow Rain with Berserk. But if the Orc has Dark Resistance and Dwarven Shield, there's nothing to be done.
And, of course, the Necromancers, even with a multiple advantage in troops, can't do anything.
But I admit that with some extremely lucky circumstances for the Necromancer and extremely unlucky circumstances for the Orc, the battle might not be a complete one-sided affair.