Solid as a Solrock (Japanese: トクサネジム！ソルロックとルナトーン！Tokusane Gym! Solrock and Lunatone!) is the 100th episode of the Advanced Generation series, and the 374th episode of the Pokémon anime. It was first broadcast in Japan on October 28, 2004 and in the United States on November 5, 2005.
Ash's battle with the Mossdeep Gym Leaders is set to begin. He calls out Swellow and Pikachu versus Tate's Solrock and Liza's Lunatone, taking into account the strange planet-filled aerial battlefield they will be using. Pikachu and Swellow appear to be at a disadvantage, but it is quickly negated by the fact that Tate and Liza aren't working together. Their Pokémon's attacks cancel each other out, and the two even collide head-on when attacking.
Team Rocket interrupts the battle, capturing Lunatone and Solrock with their robot and then escaping in their balloon. Swellow and Pikachu destroy the balloon, freeing the two Rock- and Psychic-types.
The Gym battle must resume, but the Gym has been destroyed—so it is decided they will battle by the water. Unfortunately for Ash, Tate and Liza now have their teamwork back, and they deliver a real pummeling to Ash's Pokémon. Each of his attacks is countered successfully, until he charges his team with Pikachu's Thunder and they break through Lunatone's Light Screen, finishing off the opposing team with Iron Tail and Aerial Ace and winning Ash his Mind Badge!
Tate and Liza's mother, Rachel, will referee for the match between the twins and Ash. She explains the rules of the Double Battle and gives a detailed explanation of the special field they're using. The field has mock-ups of all the planets orbiting the sun, creating obstacles that wouldn't be there ordinarily. Tate and Liza start by choosing Solrock and Lunatone, respectively. Ash instantly chooses Pikachu and Swellow for its aerial abilities. Outside, Team Rocket plots to steal Lunatone and Solrock. After Meowth’s boss fantasy concludes, he and Jessie happily rush off to the Gym to begin, but James stops them because he is concerned that Psychic types will be difficult to capture. Meowth assures him that he bought the perfect mecha for the heist from an online auction.
Back in the Gym, the battle begins. Solrock uses Tackle on Pikachu, hitting the Mouse Pokémon. Lunatone uses Tackle as well, striking Swellow. Ash then orders Pikachu to use Quick Attack on Solrock and tells Swellow to use Peck on Lunatone. As Pikachu charges into his attack, Solrock floats out of the way, causing Pikachu to crash into one of the floating planets. The same thing happens with Swellow after Lunatone moves aside. Pikachu falls down, and soon after Swellow lands on him. Things aren't looking too good for Ash at this point.
Tate and Liza are now ready for their next attacks. Solrock uses Solar Beam while Lunatone is told to use Ice Beam, however the two attacks collide and cancel each other out. The failed attacks spark an argument between the twins, stopping them from battling. Ash sees this as his chance, so he orders Swellow to use Aerial Ace on Lunatone, and it hits. Pikachu is also ordered to attack, and he lashes Solrock with an Iron Tail. Tate and Liza notice that their Pokémon are getting beaten while they quarrel, so they both rejoin the match and order their Pokémon to use Tackle attacks on Pikachu. Pikachu is about to be sandwiched by the two Psychic Pokémon, but Swellow swoops in and rescues. Consequently, Lunatone and Solrock crash into each other, which causes Tate and Liza to begin arguing again.
As the twin Gym Leaders blame each other for their constant blunders, the ground starts to rumble as Team Rocket make an unannounced appearance. The Gym’s roof caves in even more as a giant robot appears, piloted by Meowth. Liza complains about the battlefield being ruined, so Tate and Liza order their Pokémon to attack. The Team Rocket mecha fires two round cages which capture Lunatone and Solrock. The two Pokémon try to free themselves using Psychic, but Meowth laughs as he reveals the cages are made of unobtainium and reflect the attacks. Team Rocket reels in their catches and rush off to their waiting Meowth balloon while Ash and the others give chase. Ash orders Pikachu to use Thunderbolt, but his attack fails to make the distance. So, Ash has Pikachu jump on Swellow and has them pursue Team Rocket in the air. Jessie and James look worried, but Meowth tells them not to worry as he presses a button, causing the robot to fire yellow globs at the two Pokémon. Swellow presses through as Pikachu uses Thunderbolt on the mecha, causing it to release the two stolen Pokémon. Meowth apologizes to his teammates for only getting the economy package as Solrock and Lunatone crushes the mecha with Psychic. The mecha then explodes on Team Rocket to blast them off for good.
Liza admits that Ash’s match cannot go on because the Gym field was destroyed. Though Rachel suggests that they just have the battle outside, on the cliff that Team Rocket took off from, and everyone agrees that this is a good idea. So Rachel announces the continuation of the Gym battle. Pikachu uses Thunderbolt on Solrock, but Lunatone slides in front and guards it with Light Screen. The Thunderbolt gets reflected back at Pikachu, smashing him into a rocky cliff. Swellow tries to attack Lunatone with Aerial Ace, but Solrock uses Sandstorm to stop it. Brock admits that the twins are working in sync since that battle with Team Rocket. Ash also realizes this and orders his own combination, so Pikachu leaps onto Swellow's back. The now-airborne Pikachu uses Thunderbolt on Solrock, but Lunatone again intervenes and reflects the attack right back at him. However, this time both Pikachu and Swellow are hit. Tate and Liza are surprised to see that Swellow doesn't seem to be affected, considering that it's a Flying-type.
Swellow is then ordered to use Double Team, creating copies which surround Solrock and Lunatone. The two Psychic-type Pokémon fly back to back as Tate and Liza gauge the situation and order a Solar and Ice Beam combination to sweep through the duplicates. Soon they're all disposed of, though the twins are left confused about the whereabouts of the real Swellow and Pikachu. Suddenly, they see the two Pokémon flying from above, ready to strike. Solrock and Lunatone are ordered to quickly whip up another Solar Beam and Ice Beam combination, hitting Ash's Pokémon. The Pokémon start plummeting toward the ground, but Swellow is able to recover quickly enough and swoops upwards in the nick of time.
Ash weighs up his options, and after noticing the clouds forming overhead, he suddenly has an idea. He tells Pikachu to use Thunder on the clouds, confusing the Gym Leaders. Soon, the clouds spit back a streak of lightning, directly hitting Pikachu and Swellow. Ash’s duo emerge from the lightning strike supercharged and coated in golden armor. The now super-powered Swellow uses Quick Attack, so Solrock fires a Solar Beam attack on it. Swellow and Pikachu are hit, but they just ignore it and power on through. Lunatone tries to use Light Screen, but its attack is just as futile. Pikachu strikes Solrock down with an Iron Tail while Swellow uses Aerial Ace on Lunatone. Both super-powered attacks hit, and as the Pokémon’s golden power-ups fade. Rachel announces that Pikachu and Swellow have won the battle. Ash is thrilled, though receives an electric shock as hug his two Pokémon. Tate and Liza hand Ash the Mind Badge, admitting they still have to work on their combinations.