A delivery man arrives at Aurea Juniper's Lab, picking up a package. He is spooked by Black, who has been waiting all night in the rain for this. Black signs off on the delivery and opens the package, getting his pokédex and releasing the three Pokémon inside. The three immediately begin quarreling and fighting, and when Oshawott loses its temper, it beats both Snivy and Tepig. Tepig, upset and sick with a cold, runs off. Alarmed, Black gives chase.
Professor Juniper arrives at her lab doorstep to find it a mess: the two remaining pokédexes soaked, Snivy and Oshawott unconscious, and the bits of a package scattered around. Cheren and Bianca are there, wanting an explanation, and they realize that Black must have gotten here and opened the package without them.
Bianca picks up Snivy and hands it to Cheren, cheerfully declaring that she wants Oshawott, and Snivy looks like Cheren, anyway. Professor Juniper decides that they should go find Black, and they follow Tepig's footprints. They see Tepig, Black, and Black's Munna up in a tree, with Black's Braviary hovering nearby. Black is trying to coax Tepig off a dangerously weak tree branch. Black realizes that Tepig is upset because he could beat Snivy and Oshawott if he weren't sick, and Black agrees, and declares he chooses Tepig because he likes him.
Black and his Pokémon are suddenly attacked by an unknown foe who is nowhere in sight. Black has Munna eat his dreams in order to help him think, and Black figures out that their opponent is hiding in a bunch of leaves nearby. Disturbing the leaves reveals a Sewaddle, who feels that its territory is being invaded. The branch under Tepig snaps, but Tepig flips, agilely landing on subsequent branches and simultaneously nailing Sewaddle with a blast of fire.
Black asks Tepig if he accepts Black as his trainer, and Tepig agrees. Black then shouts his vows and dreams to defeat the Elite Four and Champion. He takes off on Braviary and leaves Juniper, Cheren, and Bianca behind, perhaps oblivious to their presence.
A moment later, Bianca and Cheren discover that neither of their pokédexes are functioning due to water damage, meaning that Black has the only working pokédex.