 Some NPCs offer to trade Pokémon with the player, allowing them to acquire Pokémon otherwise unavailable without connecting to another game.For example, the only way to get a Jynx in "Pokémon Red" and "Blue" (other than trading with another game cartridge) is through an in-game trade.The other way that trading is made instrumental in gameplay is that some Pokémon, like Haunter and Machoke, only evolve into their final forms when traded.