Holiday Pikachu is spawning at various places, when you find it locate it at places with high traffic around, it will be in your inventory. Also to get Gen 2 Baby Pokemons, you will need to gather new eggs.
Niantic has released Update 0.41.2 for Pokemon Go on iOS and Android. The update brings in a lot of new improvements, bug fixes, and many other things. The official changelog of Update 0.41.2 details everything you need to know.