For anyone wondering why the 4E Monster Vault dragons are getting such universal love I thought I'd dig up the 4e Young Black Dragon statblock (and also link the
5e Adult Black Dragon as the young one has neither legendary nor lair actions and the
PF1e Young Black Dragon as the 3.5 one is slightly disassembled). And then show off the parts that are neither raw generic numbers nor shared with all other dragons (which in 5e basically covers the breath weapon and lair actions)
Starting that statblock off with Acidic Blood is great both thematically (this is an acid dragon with really caustic ichor running through it's veins) and mechanically as combats get more intense as they go on. Something happens for all 4e dragon types - but acid blood is unique to black dragons (blue start spilling electricity and white get expanded crit ranges from memory). And it's only hurt enough to matter when bloodied, giving a visceral sense both of the dragon being hurt and it being even more dangerous because of it.
Next up is Aquatic. It's a minor thing, but emphasises that you can't just take a water breathing potion or ritual and be on even terms with the dragon in the water. It's genuinely good there. If you can then try to catch it or force it it onto land.
Then there's Instinctive Devouring. That thing is coming at you hard and fast. It moves twice in a turn - and how it moves is by dragon type (from memory greens make flyby attacks and blues take to the skies and lightning bolt you). Dragons are fast, mean, and unique.
Finally in the traits is the Action Recovery. Dragons aren't immune to powerful effects and can't simply no-sell them. This isn't a generic Legendary Resistance (although is shared by all dragons). But dragons are mighty enough that nothing can stop them for long.
Moving down we get to Generic Dragon Stuff (claw, claw, bite, breath weapon although acid doing ongoing as it sticks and burns is another "this isn't just a generic dragon" touch)
Then the Shroud of Gloom. Unique fell magics from the black dragon to distract and force a dilemma (whether to attack or try to get clean). At first it's fine - and then it doubles the Acidic blood damage. Every dragon colour gets their own fell magics.
Tail sweep? Every dragon gets one I think - but what triggers it is based (of course) on the type of dragon. Some are more defensive, slamming foes away and others more mean, in this case exploiting a miss.
And then Bloodied Breath. This fight just got even more serious. A free breath attack and acidic blood at half damage. All dragons get this.
No non-4e dragon comes close.