Custom commanders i wonder how would they look like...
OST
Troop training
Spotting scopes
Stuka close air support
Redistribute resources
Tiger Tank
Soviets
Guard infantry
B4 203mm howitzer
For Mother Russia
Recon overflight
T34/85 Medium tanks
I belive Stuka and Tiger will share rare/legendary status and probably we can get into dotrine only one of them. Same for ammo ->fuel. It's very powerful ability. Same like FHQ in Urban Defense. 0CP but Im sure it's rare.
Same for T34/75 and B4.
Of course there are SU doctrine with T34/85, IS and IL strike but it's made by Relic, not custom. I mean, they have to do something so we will still use stock commanders so 2 rare/legendary abilities in 1 commander will be resevred only for stock commanders.