How to calculate when accounts have different settings for No Data Zero View for NonAdjustments

That behavior depends on Account Type - Flows will work differently from Assets/Liabilities. Determine which account types you have for A and B, and then when copying data specify the View member you're actually interested in copying.

Not ideal, but so long as it is just an exceptional case for a few accounts, then you could always do a calculate that adds the value of T#PovPrior1 (if it's not the first period) on the target account, effectively doing a periodic calculation:
e.g.
if api.Time.IsFirstPeriodInYear() then
  api.Data.Calculate("A#AccountA = A#AccountB" , True)
else
  api.Data.Calculate("A#AccountA = A#AccountA:T#PovPrior1 + A#AccountB:V#Periodic" , True)
end if

obviously not particularly efficient since it has to open the previous period's data unit into memory (but that's how periodic views work anyway).   A more flexible option would be to open databuffers and test properties such as 
If api.Account.GetNoDataZeroViewForNonAdj( accountId ) = ViewMember.Periodic Then ...

and as JackLacava said, be careful about the switching behaviour on the Flow members.