Rematch at the Nacrene Gym! (再戦シッポウジム！新技炸裂！！ Nacrene Gym Rematch! Explosive New Move!!) is the 16th episode of Pokémon: Black & White.
The heroes came to the Battle Club, where Ash trains with Tepig and Oshawott, who learn new moves. Ash comes back to the Gym, facing Lenora, who evolved her Lillipup into Herdier. Like the last battle, she utilizes her Roar-Mean Look strategy. Will Ash manage to win this battle?
Don George led the heroes to the training room. Don George points at a training machine Tepig will use, so Ash sends him. Tepig is up for some hard training, though Don George pushes Ash to the machine. He explains to Ash one needs to be calm and focused on the reactions in the battle. Ash understands and goes to the machine, running with Tepig. Axew tries to go as well, but Iris catches it, as the treadmill is not a toy. Don George releases some balls, which Tepig dodges, but they hit Ash. Iris sees Ash is a kid, as he didn't dodge that. Ash asks for one more time, so Don George starts the machine. While they manage to dodge the balls, Don George releases them from behind. Tepig uses Oshawott.
At the pool, Ash comes with Oshawott, who jumps in the pool for swimming. Ash tells him they came here for training and jumps in. Don George tells them he will create currents for building stamina and muscles. Iris and Cilan come to Tepig and give him some food to eat, but see Axew is missing. As Ash swims with Oshawott against the current, Axew comes and randomly presses buttons. This causes a wave, which soaks Ash and Oshawott. Iris and Cilan come and take Axew. Ash takes Oshawott and pushes him onto the waterfall. Oshawott jumps and falls down the waterfall, causing him to learn Aqua Jet and attacks a target. Ash is excited, but falls in the water. Still, Oshawott is proud of that achievement. Later, Ash trains with Tepig, dodging the balls. Tepig uses Ember, repelling the balls and manages to learn Flame Charge.
At the Gym, Lenora senses Ash has been training hard. She sends Watchog and Herdier, as she goes to double her efforts for this battle. Ash is pleased he will face Herdier, while Lenora calls Watchog back. Ash sends Tepig, who is battle ready as Herdier is. Tepig starts with Ember, though Herdier counters it with Protect. Herdier uses Shadow Ball, though Tepig dodges some, then uses Ember to collide with the others. Tepig goes to Tackle, but Herdier Roars, switching Tepig with Oshawott. Lenora calls Herdier back and sends Watchog, who locks Oshawott with Mean Look. Ash knew that strategy would be applied once more, so has Oshawott use Razor Shell on Watchog, who fails to dodge. Oshawott uses Aqua Jet, but misses. Ash orders Aqua Jet once more, but Oshawott fails to hit Watchog. Lenora sees even if Oshawott is better, they don't have enough to defeat her.
Oshawott uses Water Gun, though Watchog uses Confuse Ray, causing Oshawott to be confused. Watchog uses Thunderbolt, hitting Oshawott. Oshawott uses Water Gun, but randomly hits the wall. Cilan knows Oshawott has taken a lot of damage and is confused, so Iris worries Ash might lose again. Oshawott uses Aqua Jet, dodging Watchog's Thunderbolt and hitting it. However, both Pokémon are defeated. Ash and Lenora call them back and sends Tepig and Herdier. Tepig uses Ember, but Herdier Protects itself, though Tepig Tackles it. Tepig goes to Tackle again, but gets hit by Shadow Ball. Lenora senses Tepig's bond with Ash, but has the duty as the Gym Leader to give everything she has. Herdier uses Giga Impact, hitting Tepig. Ash reminds Tepig he believes in him. Cilan claims Lenora is a powerful Gym Leader with a lot of combinations, but Iris wonders on whose side is Cilan on.
Herdier uses Shadow Ball, though Tepig avoids the attack, but is exhausted. Herdier uses Shadow Ball, but misses. Tepig retaliates using Flame Charge, while Herdier uses Giga Impact. Both collide and are left injured. Both stand up, though Herdier falls in defeat, so Ash wins the battle. Iris and Cilan congratulate Ash on the battle. Cilan claims one needs to train hard to win hard, with Lenora agreeing with him. She and Hawes did not expect Flame Charge to be used. Lenora presents the Basic Badge, so Ash takes it. At the Pokémon Center, Ash retrieves his egg Joy kept. Joy sees the egg is healthy and feels it will hatch soon. Later, Cilan sees the next gym is in Castelia Town. Ash already feels the victory for the third badge coming.
- This is the first time since the very first episode that Jessie, James and Meowth did not appear in an episode, aside from the first episode and the clip shows.
- Professor Oak's Live Caster: Scolipede
- The "Who's That Pokémon?" is Herdier.