Mission: Defeat Your Rival! (Japanese: 熱闘！ライバルバトルを勝ちぬけ！！ Fierce Fighting! Win Your Way Through the Rival Battles!!) is the 7th episode of Pokémon: BW Adventures in Unova and Beyond.
As Bianca, Virgil and Cameron win their respective battles, the battle between Ash and Trip continues. Reflecting on the many times he beat him all seems hopeless for Ash. Will he be able to turn the battle around, and if he does win, who will he face in the next round?
Pikachu is beaten by Serperior's Dragon Tail attack. Ash urges Pikachu on, who stands up, still able to fight back. However, Serperior's Energy Ball causes even more damage for Pikachu. Serperior uses Dragon Tail, but Pikachu manages to dodge in the last moment. Serperior continues the attacks, hitting Pikachu hard and wraps him up. Pikachu uses Thunderbolt, but Serperior slams its tail in the ground, nullifying the damage. Pikachu continues taking hits from Wrap, while Ash does not want Trip to defeat them, like he did in the last four battles, else Ash thinks the whole journey went to waste.
Elsewhere, Bianca's Emboar uses Arm Thrust and Hammer Arm, defeating Mikael's Watchog. Virgil also wins, whose Vaporeon defeated Ultimo's Crustle using Hydro Pump. Cameron has Ferrothorn use Pin Missile on Kendrick's Eelektross' mouth, negating its Crush Claw attack and winning the round. Stephan, Bianca and Cameron join Iris and Cilan to watch the battle of Ash vs. Trip. They cheer for Ash and Cameron tries to find a way for Pikachu to escape, but hurts himself thinking. Serperior goes to slam Pikachu onto the ground, but Ash has Pikachu use Iron Tail on the ground and is freed from Serperior's grasp. Pikachu uses Iron Tail, but is countered by Serperior's Dragon Tail.
Seeing his greatest problem is Serperior's Dragon Tail, Ash has Pikachu use Electro Ball and Iron Tail at the same time. After the clash, Pikachu happily jumps, for Serperior has been defeated. Trip is shocked by this great attack. Ash's friends are amazed how he won. After the battle, Ash goes to the Pokémon Center to heal Pikachu and runs into Trip, who was just leaving. Trip tells he has to be stronger than he is now, to defeat Alder. Ash shakes his hand, for they will give their best in achieving their goals. Trip bids farewell and goes on. During the night, Ash and Cilan visit the sauna. As Ash compliments Pikachu for the great battle, Cameron and Stephan visit Ash, pat him on the back, wanting to know how he won. Ash replies that it is getting hot in the room.
Elsewhere, Ash and Oshawott take a hot bath. Riolu visits them and splashes Pikachu and Oshawott. Pikachu plays back by splashing Riolu. Riolu splashes back and jumps out when Pikachu uses Thunderbolt, causing Oshawott to get electrocuted. Ash, Stephan and Cameron rush in and see Oshawott badly injured. Next day, the second round begins, with Cameron battling Bianca. Cameron thinks a bit and stretches his headband and sees whom should he send. He sends Samurott, while Bianca sends Escavalier. Samurott uses Hydro Cannon, but Escavalier dodges and uses Iron Defense. Samurott repeats the attack, but Escavalier dodges once more and repeats its own move. Samurott uses Razor Shell, though Escavalier dodges and uses Iron Defense the third time. Escavalier uses Fury Attack, though Samurott counters it with Razor Shell. Escavalier is not hurt, so Cameron thinks a bit and has Samurott use Razor Shell. Escavalier dodges, but is hit by Samurott's second attack on the head. Escavalier shakes and faints.
Bianca calls Escavalier back and sends Emboar. Samurott starts with Aqua Jet, hitting Emboar. Samurott continues with Hydro Cannon, hitting Emboar. Emboar, however, uses Attract, affecting Samurott, and hits Samurott with Arm Thrust and Hammer Arm. Samurott took too much damage and is defeated. Surprisingly, Cameron sends Riolu, making Bianca flattered by its appearance, but gets herself together. Emboar uses Arm Thrust, but Riolu leaps and jumps, evading the attacks. Emboar uses Hammer Arm, but is thrown away due to Riolu's Circle Throw. Riolu uses Force Palm and pushes Emboar away, knocking it onto the ground. However, Emboar grabs Riolu and throws him away. Riolu leaps and does not take damage, then moves away from Emboar's Flamethrower. Riolu uses Copycat, copying Flamethrower and hitting Emboar's eyes. Using Vacuum Wave, Riolu defeats Emboar.
Bianca calls Emboar back and starts crying at her defeat. Cameron cheers with Riolu, while Bianca tells he will wait for her next time for a battle. Stephan sees Cameron trained Riolu well, but Ash wants to battle Cameron even more.
Similar to Jeanette and Bellsprout in "The Fourth Round Rumble", Serperior slams the end of its body (the tail), allowing itself to receive no damage from Thunderbolt.