You’ve died due to unknown causes and as you laid on your death bed expecting nothing to come except total darkness. Instead you where not only in darkness but you smelled a lovely salty aroma like if you where at a beach. While in this darkened and blinded state you heard a voice in your head.

“My child, you have lived nothing but a plain yet sad life. For that I shall reincarnate you to another world with the body of your choice. However in this world you will be sent to the world is run by Pokémon and all alike. Now, choose who will start out as and enjoy your new life.”