Two-Deep Leadership
Two-Deep Leadership is much more than a requirement for the NQUA. In order for a troop to actually be chartered in the first place, there must be at least five youth, and at least five adults. Two of those five adults must be registered as the Scoutmaster and an assistant Scoutmaster. But this criterion goes just a bit further than that.
The assistant Scoutmaster, according to the NQUA requirements, must not only be registered, he or she must also be trained and active. That means much more than just a name on the charter. If the SA is registered and active, it doesn't count until he or she has been trained. Likewise, if they're registered and trained, it doesn't count until they are active.
The reasoning for this is simple. Having such an SA means the troop can survive if something happens to the Scoutmaster. What if he's temporarily transferred to another city for several months? Is the troop supposed to just stop functioning until he comes back? If the answer is yes, then why are we even concerned about the Scouts? They obviously aren't the focus of the program. Of course, this two-deep leadership concept also comes in handy even when the Scoutmaster isn't temporarily missing from the picture. It also supports the concept of youth protection.
Speaking of youth protection, you'll notice that the additional element of this requirement is for one adult to be assigned responsibility of youth protection training. That element is just as important as the rest of the requirement because the BSA is committed to youth protection and a quality unit should share that commitment.
Now, once again, the requirement sets a pretty low standard, but your focus should be on providing a quality program, not on earning an award. Therefore, your goal should be to have as many adults involved as possible; perhaps one assistant Scoutmaster for every patrol of Scouts, plus committee members to handle the major concerns of the committee. As I discussed under training, your goal should also be to have every assistant Scoutmaster trained, including youth protection training.