Dealing With Defensive Types! (Japanese: ミオジム戦！はがねのバトル！！Mio Gym Match! Steel Battle!!) is the 108th episode of the Diamond & Pearl series, and the 574th episode of the Pokémon anime. It first aired in Japan on December 25, 2008 and in the United States on May 30, 2009.
With Oreburgh Gym Leader Roark as referee, Ash starts his 3-on-3 Gym battle against Byron, Canalave's fossil-loving Gym Leader. Byron's first Pokémon is the Steel-and-Psychic Bronzor, so Ash sends out Chimchar, a Fire-type Pokémon. But Bronzor's Ability, Heatproof, helps protect it against Chimchar's Fire attacks, and then it uses Rain Dance to rain on Chimchar's parade! Chimchar refuses to give up, and uses Flame Wheel in a head-on charge against Bronzor's Gyro Ball—the hit knocks out Bronzor, but Chimchar barely manages to stay on its feet!
Elsewhere in the Gym, Team Rocket sneaks in to steal Byron's fossils... and the contents of his fridge! However, Byron's Omanyte, Omastar, and Kabuto blast the intruders back where they came from. Over on the battle floor, Steelix takes on Buizel; Buizel should also have a type advantage, but it can't get past Steelix's Screech. Before Ash can counter, Steelix hammers Buizel with Iron Tail, and Buizel's fight is done! Ash sends Chimchar back in to knock out Steelix with Flame Wheel, and now it's faced with Byron's prized Bastiodon.
As Team Rocket sneaks back into the Gym, only to be tossed out again by Byron's Armaldo and Cradily, Chimchar proves too exhausted to defeat Bastiodon. Now it's up to Ash's Gliscor, making its Gym battle debut! It takes a pummeling from Bastiodon, but it keeps fighting and uses its aerial advantage to get past Bastiodon's defenses. That lets it knock Bastiodon out with an explosive Fire Fang! Gliscor's first Gym battle is a success, and Ash is now the proud owner of a Mine Badge!
Ash's Gymbattle with Byron is about to begin as Roark prepares to officiate the match. Byron summons Bronzor while Ash summons Chimchar. Roark recognizes Chimchar from his battle against Paul. Chimchar immediately jumps up and fires Flamethrower. Bronzor stays in place and resists the attack thanks to Heatproof, something Byron trained for. Chimchar repeats the attack as Bronzor uses Rain Dance to change the weather and dampen Chimchar's abilities. Chimchar digs as the Rain Dance wears off. Chimchar comes out and fires Flamethrower, but Bronzor uses Gyro Ball to dodge and hit, knocking Chimchar down. Chimchar gets back up as a second Gyro Ball comes about. Chimchar meets the attack head-on with Flame Wheel. The collision creates a huge explosion, bringing both Pokémon down. Ash and Byron urge their Pokémon to get up. Though both struggle to get up, Bronzor collapses, unable to battle. Noticing Chimchar's fatigue, Ash recalls Chimchar from battle.
Byron sends out Steelix as Ash calls upon Buizel to battle. Dawn believes in the type advantage since Steelix is Steel-type and Ground-type, but everyone else knows that it may not be a big advantage. Knowing about Steelix's Defense power, Ash hesitates to make a move, but Byron's motivation gets him moving. Buizel fires Water Gun as Steelix uses Screech to both repel the attack and stall Buizel. Dawn notices how the move is the same technique that Roark's Onix used in his first battle with Roark. Steelix uses Bind to ensnare Buizel before using Iron Tail to toss Buizel and slam it to the ground. When the dust clears, Buizel still stands, but it collapses unable to battle. After checking to make sure Buizel wasn't severely injured, he recalls his Pokémon.
Ash summons Chimchar once again to battle. The Pokémon fires Flamethrower immediately, striking and causing Steelix to falter. However, Chimchar staggers, still reeling from the first round. Steelix launches Iron Tail as Chimchar back-flips to dodge. After a brief hesitation, it digs into the field, but Steelix uses Iron Tail on the battlefield to force Chimchar. Steelix tries to bind Chimchar, but it dodges before digging again. Steelix repeats its attempt, forcing Chimchar out and attempting another Bind, but Chimchar dodges again. Steelix tries to follow up, but the ground near Steelix caves and throws the Pokémon off balance, due to Chimchar's digging. Chimchar hits with Flame Wheel to Steelix's head, knocking it out. Meanwhile, Team Rocket attempts to sneak into the building again, but a Kabutops chases them away.
Byron summons his prized Pokémon Bastiodon. Ash reflects on how it stoppedRampardos's Head Smash and notices Chimchar's declining energy. Wanting to finish quickly, Ash has Chimchar launch Flamethrower immediately. Bastiodon's Iron Defense easily deflects the attack before it counters with Metal Burst, blasting Chimchar against a rock. Chimchar struggles to rise, but it falls back down, unable to battle. Ash recalls Chimchar.
Team Rocket returns to the Gym and finds a display room showing special Fossils. They run into an Armaldo and a Cradily, but the two Fossil Pokémon manage to blast Team Rocket out from the Gym with their combination of Hyper Beam and Energy Ball.
Ash summons his final Pokémon, Gliscor. Dawn questions why he didn't choose Staravia for aerial attacks, but Brock believes in Ash's choice, this being Gliscor's first Gym battle. Gliscor gets behind Bastiodon and uses Steel Wing, but Bastiodon uses Iron Defense to repel. Gliscor tries to get behind again and attempts Fire Fang, but Bastiodon's Flash Cannon hits Gliscor and halts the attack. While Gliscor hits the turf, Bastiodon charges with Iron Head. Gliscor quickly flies up to dodge, but Bastiodon comes back around and tosses Gliscor up with a second Iron Head. Bastiodon succeeds with a third Iron Head, keeping Gliscor suspended. Bastiodon fires Flash Cannon, but Gliscor spreads its wings to dodge before jumping on Bastiodon's back, grabbing its horns and landing a Fire Fang.
Bastiodon tries to throw Gliscor off as Gliscor hangs on and repeats Fire Fang. Bastiodon tosses it off and fires Flash Cannon, but Gliscor uses its tail to trip Bastiodon and causes the attack to miss. Bastiodon and Gliscor are both exhausted. Both Ash and Byron know that the last hit will decide the outcome. Bastiodon charges with Iron Head. Gliscor uses X-Scissor to stop Bastiodon, but it fails. Ash tells Gliscor to take cover behind a rock, so Byron has Bastiodon smash it. It does so, but Gliscor managed to fly up at the last moment. Bastiodon fires Flash Cannon, but Gliscor dodges and uses Sand-Attack to cloak the area before hitting with a close-range Fire Fang. The explosion tosses both Pokémon aside, but Bastiodon falls, unable to battle. Ash wins the match as Gliscor hugs Ash. Afterward, Roark and Byron congratulate Ash on his victory. Byron gives Ash the Mine Badge, which he gladly accepts.
This is Gliscor's first Gymbattle, and as of this episode, Ash's entire team has now participated in at least one Gym battle.
As of this episode, Buizel has participated in more Gym battles that any other member of Ash's Sinnohteam (including Pikachu, if Gym battles from other regions aren't counted). However, it also ties with Chimchar, if its battle against Roark during its time with Paul's team is counted.
Team Rocket does, however, recite part of a variation of their motto without the background music. Before they could finish, though, Meowth cuts it short and, while breaking the fourth wall, says, "Look, kids, since you know what comes next, let's cut to the chase."
In multiple scenes, the stripes on Byron's pants are colored gray instead of yellow.
After colliding with Flame Wheel and Gyro Ball, respectively, both Chimchar and Bronzor initially appear to fall, even though Bronzor was the only one to actually fall.