Nothing will take away just how special the first generation of Pokémon was, but Generation II was where Pokémon really started to open up. The formal introduction of dual-types (Charizard can now fly! (I know he could in Yellow, but he couldn't in Green/Red/Blue)), and the implementation of a day and night cycle created different ways to play. For the first time, the time of day mattered—certain Pokémon could only be caught at certain times, for example. This made gameplay more frustrating and more interesting. On top of having day and week cycles, Generation II expanded on the Friendship/Happiness system that was introduced in Yellow, making Pokémon grow via their "devotion" to their trainers.