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Suffice it to say, battle is also an important aspect of Pokémon. The game uses a turn-based battle system where the Pokémon in your care do all of the actual fighting. For each turn, you may perform a single attack or use a single item. Pokémon can memorize only four different attacks at any given time, however, so if they run out of PP for a particular move or are nearly unconscious, you can always swap them with another Pokémon in your pack. Although you're allowed to bring only six Pokémon into battle, PCs located at every Pokémon Center let you store approximately 250 additional Pokémon for later use. Pokémon will learn new attacks as they grow and evolve, but you can also acquire additional skills, in the form of TM and HM items, after hallmark battles or from special shops scattered throughout Johto and Kanto.
In addition to the 15 original Pokémon types (normal, fire, water, grass, bug, ground, electric, flying, fighting, ice, dragon, psychic, ghost, poison, rock), two new types were introduced to the mix by the Gold and Silver series: steel and dark. Pokémon Crystal contributes nothing new in this respect, but the strategic pairing of strengths, weaknesses, or stalemates based upon these innate proclivities remains a clever and enjoyable aspect of gameplay.