The last two are subjective, since the second means which units are better or worse, and there is a great deal of debate over this. This has often been the bane of East Bloc troops, cursed to rely upon the inflated price of their 15 point BTR transports. Even with less glaring examples the same can happen, the most common example being infantry and their transports - infantry on their own may be great, but if they have bad transports, they do not work well. North Korea has an excellent bomber with the B-5, but it lacks SEAD to enable it to survive in a defended air space: as a result North Korea's air force lacks the synergy needed to make it work. It is possible to have excellent units, but if they don't work together well, then they are useless. The final feature is how well all of these work together.
Or East German Mot Schutzen which are 5 points cheaper than Chinese Lu Zhandui, despite being essentially the same.
WARGAME RED DRAGON SERIES
There are plenty of examples of units which fill the same role in Wargame, but where one is simply far better - such as the Soviet series of BTR-70 and 80 transports, which fill the same role as fast motorized transports with autocannons on them, the Finnish KT series, but where the Finnish KT series with their powerful bushmaster autocannons are simply infinitely better than Soviet 14.5mm KPVT heavy machine guns. The units must work and perform well, and not be too expensive. If it does have these counters, then what it has has to be reasonably efficiency. For a faction to be viable, it must have some sort of counter to each threat it faces. It doesn't matter that they are good at everything else, because this critical weakness will be exploited by the enemy, and they will be mercilessly bombed and helicopter attacked into oblivion. There is only one problem - they have no anti-aircraft weapons. Consider a faction in Wargame which is excellent at everything - at destroying tanks with superb high AP, heavily armored super heavies, at annihilating infantry with great fire support options and powerful infantry of their own, with great reconnaissance and superb artillery.
The most important trait in my opinion, is that of being able to respond flexibly to any threat. In Wargame, there are three crucial criterion for any faction that determine how good it is