How difficult should Zapdos and Moltres be if similar to Articuno which has been duoed and soloed (with mushrooms)?

Indications were that Zapdos and Moltres should be more difficult than Articuno because of the counters available. However, predictions for difficulty on places like pokebattler were much harder than a potential duo/solo. With what was seen on Articuno, how many people will likely be needed for the other two birds, and how much of the group will need to actually be good? I can get a group of four - no problem - but four people who invest in ideal counters and properly coordinate is an entirely different subject. I'm going to try Articuno tomorrow with one well powered party, and three other people at various lower investment levels. I'm curious how much harder things would be expected to be for the other two to see if I should make attempts with a group of casuals for those two as well.