#No the Couatl cannot gain Spellcasting using Change Shape
> [The Couatl] gains any Statistics and capabilities (**except Class Features**, legendary actions, and lair actions) that the new form has but that it lacks.

###Spellcasting is a class feature, even for monsters

According to the [introduction to the Monster Manual][1]:

> 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...
> 
> The monster has a list of spells known or prepared from a particular
> class. [...] The monster is considered a member of
> that class when attuning to or using a magic item that requires
> membership in the class or access to its spell list.

So the rules say that Spellcasting is a class feature even with monsters. In fact, the association with a class seems to be the distinguishing difference between Spellcasting and Innate Spellcasting (and there [is indeed a difference][2]). In this case, the Couatl is considered to be a member of the Wizard class even though it doesn't say Wizard anywhere on it stat block.


This has been clarified and confirmed by [Jeremy Crawford][3]:

> The Spellcasting trait in monsters is associated with a class, as explained in the introduction to the Monster Manual. That's a class feature.

Because Spellcasting is a class feature, the Couatl will not get this ability when it uses Change Shape to turn into a Hobgoblin Devestator.


  [1]: https://www.dndbeyond.com/compendium/rules/mm/introduction#SpecialTraits
  [2]: https://twitter.com/JeremyECrawford/status/845737875211673601
  [3]: https://twitter.com/JeremyECrawford/status/928771874678435840