SM043: When Regions Collide!

- (ジムバトル！Ｚワザ対メガシンカ！！) is the 43rd episode of Pokémon the Series: Sun & Moon.

Synopsis
Ash and his Alola friends challenge Misty and Brock to a gym battle at the Cerulean Gym for an extracurricular lesson.

Episode Plot
Professor Kukui along with Ash and the group arrive at Cerulean City. As they enter at the newly rebuilt Cerulean City Gym, Ash was surprised to see the Gym was a mixed with brown rock interiors until they encounter Misty's Psyduck. Both Ash's Pikachu and Brock's Geodude happily reunite with their old friend as Professor Kukui informs them that both Misty and Brock are going to have a Gym battle against them as part of their extracurricular lesson when both Misty and Brock show them both a Boulder and Cascade Badge and are willing to give it to them if they could beat them in the Gym battle much to their excitement. Misty also reveals that Ash beat them from the very beginning when he acquired both badges as Kiawe questions him making Ash reveals that he beat them in a Pokemon Gym battle to get the badge to participate in the Indigo League. After Lana, Mallow and Ash pick Misty while Sophocles, Lillie and Kiawe pick Brock, Misty uses her Psyduck to fight both Lana's Popplio and Mallow's Steenee in a handicap. As both of their attacks make Psyduck suffer from a headache, it unleashes its newly-learned Water Gun at Popplio who manages to use Bubble Beam and absorb the water, and used it as a counter-attack on Psyduck, entrapping it in a large bubble. Psyduck was hit from Steenee's Magical Leaf causing Psyduck to fall head first into the ground causing it a severe headache as it unleashes Confusion on both Pokémon only to be calmed by Misty despite it hurting its head severely.

Thereafter, Brock uses his Geodude to face Lillie's Alolan Vulpix and Sophocles' Togedemaru as the latter unleashes its Zing Zap but to no effect as Brock tells him that Kantonian Geodude are Rock and Ground-Type after Sophocles mistaken this as an Alolan type and doesn't effect on electric attacks much to his dismay as Lillie lets Snowy unleash its Powder Snow only for Geodude to disperse the attack using its newly learned Gyro Ball, surprising them. Professor Kukui also informs them about the Pokemon battles as he allows Kiawe to face Brock while Ash to face Misty in the actual Pokemon battle.

Both Brock and Kiawe became very competitive when it comes to an actual Pokemon battle. Kiawe releases Turtonator while Brock does the same to release his Steelix. Ash was surprised to see his Steelix again as Rotom Pokedex tried to record it. Sophocles knows about the Steel-Type's weakness being fire as Turtonator has the advantage. Although, Lillie warns him that Steelix's ground type attacks is very effective against Fire-Types. Ash cheered Brock on the battlefield as the battle begins. Kiawe let Turtonator unleash its Flamethrower at Steelix. Despite its super effective damage, Steelix is able to withstand the attack as Brock allows to use its newly learned Gyro Ball to disperse the flames and catch Turtonator off guard using its Bind but it broke free using its Shell Trap to knock it off. Kiawe was impressed about Brock's strength as Turtonator uses its Dragon Tail only to be damaged by his Steelix's Dig causing super effective damage followed by a Slam from the tail. Kiawe does not give up the fight despite Turtonator's serious damage. Brock also taunts him for being desperate to win as he is very knowledgable about the Z-Moves and also decides to show his full strength. He then removes both his vest and shirt to reveal the necklace on his neck with a Key Stone embedded as its pendant, surprising everyone including Ash as he calls himself being both a strong and a rugged man. Brock rips his necklace to activate his Key Stone to mega evolve his Steelix into Mega Steelix much to Kiawe's horrible shock. Kiawe activates his Z-Ring to unleash Turtonator's Inferno Overdrive at Mega Steelix but to no effect as it withstands its powerful Z-Move and Brock confidently defeats Kiawe by defeating his Turtonator using Mega Steelix's Stone Edge causing super effective damage in an explosion as Turtonator fainted after the smoke clears despite trying to use its Dragon Tail to disperse the powerful attack. When Brock put his shirt and vest back on after his Steelix reverted back to normal and was recalled, he saw Kiawe apologize to his Turtonator for being defeated only to be headbutted by his Alolan Marowak as Brock tells Kiawe that his Marowak was angry because they lost to him.

Now its the battle between Ash and Misty as he uses Pikachu to fight her Gyarados. Both Pokemon are equally matched with their abilities as Pikachu gives itself the upper hand using Quick Attack until her Gyarados unleashes its Rain Dance when Pikachu attempts to hit with Electro Ball as the move being disperse by Gyarados' Hurricane. Misty reveals the Key Stone hidden behind her hairclip on her ponytail as she mega evolves her Gyarados into Mega Gyarados and uses the advantage to deal Pikachu on the water as well as trapping him using Hurricane so that Pikachu's Thunderbolt won't be effective. Despite the strategy, Pikachu is able to jump at the center of the Hurricane and defeat her Mega Gyarados by unleashing its Z-Move the Gigavolt Havoc causing super effective damage as it reverted back to normal, fainted.

After the lesson, both Brock and Misty give them a Boulder and Cascade Badges to Mallow, Sophocles, Lana, Lillie, and Kiawe and Ash was glad to see them helping them out as the special guests. Professor Kukui plans to have a Pokemon League in Alola too.Professor Oak finally bids farewell to his cousin as everyone finally depart back to the Alola region at Melemele Island. Before they departed back to Alola, Ash tells both Brock and Misty to visit him sometime at the Alola region which they agreed. At the plane heads back to the Alola region, Jigglypuff was last seen sleeping at the top of the plane. The next day, Team Rocket were still at Bewear's grasp while in the middle of the ocean as it takes them back to its den.

Pokémon

 * Brock's Mega Steelix
 * Misty's Mega Gyarados

Item
Steelixite

Trivia

 * "Who's that Pokémon?:" Mega Steelix (JP)
 * The Poké Question, hosted by Ash, asks who is the Pokémon that Pikachu battles with. The answers are Starmie (blue), Gyarados (red), Goldeen (green), and Psyduck (yellow). The correct answer is the red one, Gyarados.
 * The preview for this episode, shown in the next episode preview segment at the end of the previous episode, is narrated by Professor Oak and Samson Oak.
 * Brock fights Kiawe in shirtless during their Gym battle as he resembles his game counterpart in Pokémon Red and Blue.