My Circle of the Moon druid reached Level 10.
If I use Elemental Wild Shape to transform into an elemental, do my attacks count as magical?
Rules as written, it seems like the answer is No, as "Primal Strike" reads:
Starting at 6th level, your attacks in beast form count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.
But is this intended?
On a second reading of Circle of the Moon, maybe it is intended. That conclusion is supported by the fact that you're not merely adding the elementals to your list of beast shapes, but that the transformation process is a completely separate mechanic that just happens to cost (two, which is also novel) wild-shape-uses.
At 10th level, you can expend two uses of Wild Shape at the same time to transform into an air elemental, an earth elemental, a fire elemental, or a water elemental.
On a third reading it maybe is unintentional after all (I wish I could just give you an answer. How did I come to this conclusion? When reading through the other Circles (namely Spores and Wildfire) one bit stood out to me:
rather than transforming into a beast form
This wording is actually unnecessary. As opposed to circle of the Moon it would be quite obvious without this bit that you are not transforming but spending the wild shape charges on something else. But they still put it there, in both cases, to make it absolutely clear that you're doing something that is specifically not the beast form transformation that "wild shape" usually entails.
However, this sentence (which is copied 1 for 1 from Spores to Wildfire) is missing in Circle of the Moon's feature description. [The fact that it also says "expend ... uses" like the other two does counter this conclusion a bit]
Tl:dr: It's a mess
There's no way to know the intent without asking the designers. As written, as you say, it seems pretty clear, you're not taking a beast form (and there is no language that says the elemental form is classified as a beast form for this purpose), so the attacks are not magical. That said:
It generally doesn't matter for the fire elemental. (Almost?) All resistances that are overcome by magical weapons only apply to the physical damage types, slashing, piercing, and bludgeoning, so fire damage being magical or not doesn't matter (enemies that are resistant/immune to fire damage have the same protections regardless of whether it's magical fire or not).
For the others, as a DM, I'd use rules from earlier editions that a creature's attacks count as magical if the creature themselves has resistance to non-magical attacks (e.g. the old 1E/2E rules allowed a creature that was immune to damage from less than +3 weapons to have its own attacks count as +3 weapons; it made it so werewolves could fight each other and actually injure one another without toting silver weaponry), and all of the elementals have resistance to non-magical physical attacks of this sort, so they'd qualify if you used that house rule.
The most sensible interpretation is that “beast form” also includes the elemental form, because many other core rules also only mention “beast form” or “beast shape”.
For example, the rules for Wild Shape include
You can stay in a beast shape for a number of hours equal to half your druid level (rounded down).
With a strict reading of “beast shape”, this would not apply to Elemental Wild Shape either and mean that the druid could be an elemental indefinitely.
