Orcs – discussion about the race.

with three native Castles?
or on a map with gold mines and Utopias?
I think in a game like this, the opposite is true; the Orc has little chance against the Knight.
especially when all three Castles are built and training is in full swing in each of them.

If there are a lot of mines, the situation changes if you can't undermine the economy. Against the Knight, Roar helps a lot. I don't know, but maybe it's worth leveling up the Call skill against him, so that he can Roar more often and use Fury?

as for the Necromancer on a map with non-native Castles, I don't know, maybe he will tear them apart. or maybe not, if you don't count all sorts of summons, of course...

With Summons, of course, with his native ones.

especially if you use additional Castles only to get low-level troops.

There will be enough money to buy the full growth of 3 Castles up to level 6 (and level 7 Necromancer dragons can go to hell), as long as there are resources to build them, or the Castles are already in a combat-ready state when you take them from the AI.