How does Wild Shape work with special ways to calculate your AC?

Question

Among the effects of Wild Shapes, these two:

Your game Statistics are replaced by the Statistics of the beast, but you retain your alignment, personality, and Intelligence, Wisdom, and Charisma scores. You also retain all of your skill and saving throw proficiencies, in addition to gaining those of the creature. If the creature has the same proficiency as you and the bonus in its stat block is higher than yours, use the creature's bonus instead of yours. If the creature has any legendary or lair actions, you can't use them.

You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so. However, you can't use any of your Special senses, such as Darkvision, unless your new form also has that sense (PHB p.67, "Wild Shape")

Seem to come into conflict with each other when things like Draconic Resilience:

When you aren't wearing armor, your AC equals 13 + your Dexterity
modifier. (PHB p.102, "Draconic Bloodline")

and Barbarians:

While you are not wearing any armor, your Armor Class equals 10 + your Dexterity modifier + your Constitution modifier. You can use a Shield and still gain this benefit.

and Monks:

Beginning at 1st level, while you are wearing no armor and not wielding a Shield, your AC equals 10 + your Dexterity modifier + your Wisdom modifier.

and Stone Sorcerers:

As an action, you can gain a base AC of 13 + your Constitution modifier if you aren’t wearing armor, and your skin assumes a stony appearance. This effect lasts until you end it as a bonus action, you are incapacitated, or you don armor other than a shield.

How would these resolve?

Answer 1

In general: You chose which AC to use

The answer to your question is very straight forward:

If you have multiple features that give you different ways to calculate your AC, you choose which one to use. (PHB)

Monk/Druid - Can use either

For Monks specifically there is an official ruling by Jeremy Crawford:

The druid/monk could use Unarmored Defense or the beast's AC calculation.

Barbarian/Druid - Can use either

Barbarian unarmored defense is worded exactly the same as the monk's so the previous ruling is applicable here as well.

Draconic Resilience - Beast's AC except, maybe, if the beast has scales

You can't use features that the beast form doesn't have

Per the PHB

can use them if the new form is physically capable of doing so

and Jeremy Crawford

Wild Shape: keep your racial traits, unless told otherwise or they require external features (wings/hands/etc.) the new form lacks.

You cannot use any racial features that your beast form does not have.

Draconic resilience depends on specific physical features

The Draconic Resilience feature says:

parts of your skin are covered by a thin sheen of dragon-like scales. When you aren’t wearing armor, your AC equals 13 + your Dexterity modifier. (PHB)

Note that this effect is predicated on the presence of dragon-like scales on your skin specifically. This means that this feature requires those to be present.

If you wild shape into a beast with skin and fur, the best thus lacks the necessary physical traits to make use of the draconic resilience.

Very similar official ruling

Jeremy Crawford made a ruling about a lizardfolk's natural armor feature. The description of which is:

You have tough, scaly skin. When you aren't wearing armor, your AC is 13 + your Dexterity modifier. (VGtM)

Note how it is very similar to the description of draconic resilience.

His ruling was:

The lizardfolk's Natural Armor specifies anatomy: tough, scaly skin. It doesn't apply if you're wearing a beast's skin in Wild Shape.

However, if the beast has scales it might qualify (DM's choice)

Note that in the above ruling Jeremy Crawford specifically says "wearing a beast's skin". It is possible that if the beast has scales (for example the crocodile or ankylosaurus) that it might qualify as now having the necessary physical feature (scales) thus allowing you to use draconic resilience.

This will likely come down to a DM call as to whether any of the creatures on the list have a "thin sheen of dragon-like scales", but it seems like a reasonable ruling to allow.

Stone Sorcerers - Should be able to use either (if the beast has skin)

Per the discussion above about draconic resilience, if you turn into a beast that has skin you should be able to chose between the Stone’s Durability or the beast's AC.

Note: Stone Sorcerer is UA material so it is non-final.

Answer 2

Most likely a DM's call

This is a conversation my DM and I have had in the past. We have never come up with a definitive answer due to it never actually coming up in play. The Feature does state that the scales form on the skin, and when wild shaping a the new form could use other features such at Rage or Divine Smite (since there is no component cost for Divine Smite). It would make since that another class feature like Draconic Resilience would also carry over. If it was gained from the Lizardfolks Natural Armor then it wouldn't carry over.

Over all, like stated before, I feel like this one is a DM's call until we get an official word from Wizard's.