>>15186248Frequency of Starter choices, I suspect.
Moltres shows up if you picked Froakie, and Articuno appears if you picked Chespin. Froakie was the most popular starter choice, Chespin is the least.
Source: Greninja is pretty clearly the "Charizard Choice", especially among young children. Ninjas are cool, just like Dragons are cool. Delphox would/should fall into the Venusaur slot; i.e., the best starter from a Gym advantage perspective (SE on Bug, Fighting, Grass, and Ice, resists Fairy and Psychic) but being too "girly" looking for 5-10 year old male players... except it doesn't, because of the popularity of Fire types and the fact that Fennekin is really fucking cute. Meanwhile, Chespin is a Grass-type, which is objectively worse than Fire and Water overall, Quilladin is the least appealing design out of all three starter families, and Chesnaught looks rather awkward and may be dismissed as a weird mummy dude with a really big shell.
If it matters, I picked Froakie, but Chespin is easily my second favorite. In fact, I wish I'd started with Chespin because of Friend Safari giving you the better Frog Ninja anyway...