What is considered a class feature for a monster for the purpose of Change Shape?

Question

It's well understood that Spellcasting in a creature's stat block is a class feature. For the purposes of Change Shape and similar abilities where the term "class features" has mechanical importance, are there any other class features in official monster stat blocks? The wording in Monster Manual implies that such things could exist, but do they, and if so how do we tell?

Examples of creature stat blocks with named abilities that might be class features (vs classes where an equivalent ability is a class feature):

• Kobold Scale Sorcerer's Sorcery Points vs Sorcerer?
• Would a shape changed Couatl be able to sorcerize its innate spells?
• Drow Shadowblade's Shadow Step vs Shadow Monk?
• Firenewt Warlock's Imix's Blessing vs Fiend Warlock's Dark One's Blessing?
• Githzerai Anarch's Psionic Defense and Unarmed Strike vs Monk? (I don't think we're in class feature any more.)
• NPC Assassin's Assassinate, Evasion, and Sneak Attack vs Assassin Rogue?

Answer 1

The only trait that is a class feature in the Monster Manual is Spellcasting

Since there is no general definition for a class feature, something is only a class feature if a rule says it is. The class features in the Player's Handbook, and other supplements, are clearly labelled as such:

As a [class], you gain the following class features.

The "Introduction" to the Monster Manual talks about monster traits, where the only mention of class features lies in the Spellcasting trait (emphasis mine):

A monster with the Spellcasting class feature has a spellcaster level and spell slots, which it uses to cast its spells of 1st level and higher (as explained in the Player’s Handbook).

All other traits are just special traits with no connection to class features. As such, only if the form assumed has the Spellcasting trait or PC-levels will any traits be blocked by the relevant clauses of Change Shape.

Answer 2

At the very least, monster abilities that share a name with known class features

The MM states

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

From this, we know that at the very least, Spellcasting is a class feature. The MM also states

A monster’s type speaks to its fundamental nature. Certain spells, magic items, class features, and other effects in the game interact in special ways with creatures of a particular type.

Note that "class features" is plural, and why not just say "spellcasting" if that's the only class feature? From this we might conclude that there are other abilities that count as class features.

I will not speculate which monster features are related to class and which are related to race or other origins - I assume this ambiguity is an area that is intended to be left to the DM's discretion. However, there are some known class features that appear in monster statblocks.

We know from the PHB that the Abjurer's "Arcane Ward" is a class feature. The Abjurer statblock in Volo's guide also has an "Arcane Ward" ability. The text of this ability is slightly different from the class description text, but it is reasonable to assume that this is only to save the DM from having to do math. Note that the Spellcasting class feature for monsters also has different text.

This is the same for the other Wizard subclass statblocks in Volo's, who all have an equivalent 2nd or 6th level wizard subclass ability with the same effect and name as the original class description (Conjurer has Benign Transposition, Diviner has Portent, Enchanter has Instinctive Charm, etc.). These statblocks are all clearly modeled after classes, and they have some of the very same abilities, so it would be downright bonkers to claim that these are not class features.

If these abilities that share a name between class description and monster statblock are class features, then it only follows that any monster ability that shares a name and has essentially the same effect as an ability on a class description is a class feature.

Answer 3

Take a look at shapechange spell and notice that it specifically restricts the spellcasting trait AND class features, while the dragon's change shape does not.

Considering the way that D&D 5e rules were intended to be clear and literal (normal English) in their implementation, dragons should be able to transform into a humanoid with the spellcasting trait and gain that trait temporarily.