Two special Chiristmas Pokémon!

How about a Chiristmas Caterpie, It can be obtained in a game-event called

A chiristmas adventure! In that part of the game you'll be able to see/capture Suicune, Articuno 

and... a Shiny Pokémon, but i dont know what for now...

(This special pokémon can not evolve to metapod, but he has special moves, better stats and he's and Bug and Ice type)

In the after game adventure, a special Pokémon in the place of Caterpie will be a stantler, the Reindeer Pokémon!

(This special pokémon is also an Ice-Type, and he can know Fly)