(All information from Bulbapedia)

Chespin

  • Chespin is the first Grass-type starter Pokèmon that is based on a mammal.
  • Chespin is the only regional Grass-type starter Ash hasn't obtained in the anime.

Fennekin

  • Fennekin is the only Pokèmon with a base stat total of 307, making it the only unevolved starter Pokèmon with a unique base stat total.
  • Fennekin and its evolutionary relatives share their category with Vulpix and Ninetales. They are all known as the fox Pokèmon.

Froakie

  • Froakie is the smallest unevolved starter Pokèmon.
  • Froakie has the highest base speed of all unevolved starter Pokèmon.