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>This movie causes a causal loop and a grandfather paradox. Since Sammy went 40 years ahead in time with no certainty of getting back, an alternate timeline exists in which he never returned to his time to become Professor Oak as we know him. Even though he does succeed in going back, this makes Ash and Pikachu's pairing either a coincidence or intentional manipulation on Oak's part. In either case, there is a paradox in which Oak could not have conceived of giving Pikachu to Ash without having met them as a boy, and Ash could have never owned Pikachu if this didn't happen (unless it was a coincidence). In other words, Ash received Pikachu because Oak met him as a boy, went back to his time, and then 40 years later gave Ash a Pikachu with which to meet his younger self
