When you start the game go to cobalt beach you will need to get a pass to get the bus there if you do not have the pass go on the channel shop'n'squirtle and buy it when you are on the beach look out to sea you will see an island tell pikachu to go there by clicking on it he will almost drown and he will swim back to shore keep practicing and pikachu will learn how to swim this will take a while and he will swim to the island and call you over click on the island to go there and you will see a strange pokémon crying because its stranded click on it and answer its question and it will follow you take it to shore and it will become a friend and it will stay in your yard or field and when you visit it it will become very happy and play with pikachu.