Spolier alert! The hidden info may spoil your fun of playing.
Noah tells Ash about Gary Oak and The Encounter (forgetting to mention the 5 million Poke Dollars), he decides that he will have to save him, but tells Noah that he can't come, Noah is upset and runs off to Digglet's Cave anyway. Later that day, Ash goes into the cave, and Noah follows suit undetected, and can't find Ash, but a few Team Rocket members mistake Noah for Ash and fight him. After the fight, Ash finds Team Rocket with Oak, everything goes well, until Pichu accidentally yells "PICHU!(SO COOL!)"