Given that Dragon0 is already slightly overcosted imo, and Horizontal omniswap doesn't seem to be very useful I'd cost A at 14.
If B gets into position it can in theory create free kills, but therefore you need to avoid it getting attacked first and that's not too easy. It's a bit more mobile than Paladin0.
On the other hand it can't fulfill Paladins defensive swap task. Its destroy also isn't (Unblockable), so it can't make the typical horizontal Paladin multi forks.
Overall B is better than Paladin0, but worse than Paladin+, I'd cost it at 11.
C has mobility and attack power between Paladin0 and +, but it shares the (Unblockable) Attack squares with Ninja, in difference to Ninja it hasn't King coverage tho.
It has to be noted in that context, that Ninja already is a very overcosted piece in CEO, while it covers more important squares than C.
C is much better at giving repetitive checks than Any tier of Ninja tho, once it gave its first usually avoidable check.
I'd cost C at 13 and think it would still be on the weak side.
D is Paladin+ with gimmick backwards swap/mobility/attack and range3 Attack forwards. Also its forward squares are all (Unblockable) swaps.
Yet again it's quite good at repetitive checks once it gets to check.
It's also a straight up better version of Paladin+ and it can also easily compete with Paladin+++.
So I'd cost D at 16.