If a dragon uses Change Shape to turn into an Evoker, does it gain/have the material components for its spells?

Question

Nuanced question about true polymorph (TP) and dragons changing shape:

I have a wizard who has a simulacrum (sim). Wizard TPs the sim into an Adult Bronze Dragon, which can then Change Shape into a humanoid or beast of its CR or below. TP says the sim retains personality and alignment, so it still holds loyalty to me. I have it transform into, say, an Evoker (CR 9 humanoid wizard with spellcasting prepared) from Volo's Guide to Monsters.

One of the Evoker's prepared spells is stoneskin, which requires a material component of 100gp's worth of diamond dust. Does the dragon gain the Evoker's material components automatically upon transforming, or will I have to provide them some other way?

Answer 1

Change Shape excludes the Spellcasting class feature

The last sentence of the Adult Bronze Dragon's Change Shape reads (emphasis mine):

Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.

Does Spellcasting count as a class feature? The 2018 D&D Basic Rules PDF says the following about monster special traits (p. 113; emphasis mine):

Spellcasting

A monster with the Spellcasting class feature has a spellcaster level and spell slots [...]

The monster has a list of spells known or prepared from a particular class.

Therefore, a dragon using Change Shape to become an Evoker does not have access to the Evoker's Spellcasting.

Rules sources disagree on "class feature" vs "special trait"

The latest digital sources agree that Spellcasting is a "class feature". The physical Monster Manual is a weird outlier, though. It went from "class feature" in the first printing, to "special trait" in the fifth printing*.

The November 2018 Monster Manual Errata PDF does not mention any changes, so the most likely scenario is that an error was introduced by the time of the fifth printing, due to copying from older digital sources (like the SRD).

Additionally, all sources include the line

The monster has a list of spells known or prepared from a particular class.

...which indicates that Spellcasting is a class feature. Lastly, Jeremy Crawford states that the Spellcasting trait in monsters is a class feature. His tweets are no longer considered official rulings, but they can still provide insight into the intent behind certain rules.

What follows is a breakdown of which sources say "class feature" and which say "special trait":

Class Feature

A monster with the Spellcasting class feature has a spellcaster level and spell slots [...]

• The 2018 D&D Basic Rules PDF
• The first printing of the physical Monster Manual
• The Monster Manual on D&D Beyond

Special Trait

A monster with the Spellcasting special trait has a spellcaster level and spell slots [...]

• The SRD (last updated in 2016)
• The fifth printing of the physical Monster Manual
• The Basic Rules on D&D Beyond

(Credit to V2Blast for pointing out these differences in the comments.)

^{* (The fifth Monster Manual printing is denoted by "9 8 7 6" below "First Printing: September 2014" on the back side of the first page. The first printing would be "9 8 7 6 5 4 3 2", the second printing would be "9 8 7 6 5 4 3", etc.)}

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If Change Shape didn't exclude Spellcasting, you would form with the necessary components

The Monster Manual has an entire section titled "Statistics". In it, the last subheader reads (MM, p. 11):

Equipment

[...]

If a spellcasting monster needs material components to cast its spells, assume that it has the material components it needs to cast the spells in its stat block.

Material components count as equipment, equipment counts as statistics, and Change Shape replaces the dragon's statistics, so the dragon would also form with any necessary material components.

(Credit to Rubiksmoose's answer to "What all is included in a creature's game statistics?".)