Early reports credited 浅田裕二 Yūji Asada as storyboarder and assistant director and 岩根雅明 Masaaki Iwane as animation director.
The Grass Menagerie! (Japanese: ハクタイジム！VSナタネ！！Hakutai Gym! VS Natane!!) is the 37th episode of the Diamond & Pearl series, and the 503rd episode of the Pokémon anime. It first aired in Japan on June 7, 2007 and in the United States on November 17, 2007.
The time has come for Ash's Eterna Gym Battle with Gym Leader Gardenia, who's a Grass-type Pokémon expert. The battle will be 3-on-3, starting with Ash's Turtwig against Gardenia's Cherubi. The sun is out and that means Cherubi's Chlorophyll ability gives it a speed boost, so before long Ash recalls Turtwig and swaps in Staravia. Meanwhile, Team Rocket is digging into the Eterna Gym in hopes of stealing Pokémon, but they end up hitting a network of underground tunnels instead. There they meet an Underground explorer who convinces them to help him dig for sphere and other buried treasures—too bad he doesn't plan on sharing the loot!
Back on the surface, it's Ash's turn to use the weather to his advantage. He has Staravia dive at Cherubi, using the glare of the sun as a distraction, and Staravia wins this round. Next up is Gardenia's Turtwig: Ash has a strategy to neutralize her Turtwig's speed, but Turtwig still manages to knock Staravia out with Leech Seed.
Now it's Ash's Turtwig against Gardenia's Turtwig! These Pokémon have faced each other before and neither one wants to lose. Ash's Turtwig wins this round, but it's been weakened by a Leech Seed from Gardenia's Turtwig. Gardenia's Roserade is then able to defeat Ash's Turtwig with ease, but that just means Ash's Aipom is ready to go next! More of Ash's quick strategizing wins the final round, and now he's earned his Forest Badge!
The Gym battle begins, set for a three-on-three battle. Ash praises Pikachu for standing down on this one. Gardenia summons Cherubi as Ash sends out Turtwig. Ash goes first with Tackle, but Cherubi dodges easily. Turtwig follows up with Razor Leaf, but Cherubi dodges effortlessly and gets behind Turtwig. Brock notices the harsh sunlight enabling Cherubi's AbilityChlorophyll to double Cherubi's Speed. Cherubi fires an instant Solar Beamattack but Turtwig jumps up to dodge. Thinking it will take time to fire another, Ash commands Turtwig to use Razor Leaf, but Cherubi fires another quick SolarBeam, negating the Razor Leaf and hitting Turtwig. Cherubi uses Magical Leaf, but Ash quickly recalls Turtwig, Gardenia praising his decision to substitute. Underneath, Team Rocket continues digging as they emerge into a lit underground tunnel. A miner approaches and Team Rocket recites its motto. The miner reveals that there are treasures underneath, Shards and Spheres among them. He recruits Team Rocket to help find the treasure and split the profit.
Meanwhile, Ash sends out Staravia. Cherubi launches Solar Beam, but Staravia dodges and uses Wing Attack, but Cherubi dodges and fires Solar Beam. The quick charge fails as clouds now obscure the sun. Cherubi switches to Magical Leaf as Staravia bolts straight up, eventually getting out of range. Staravia turns around and descends slowly with Wing Attack, stunning everyone. Staravia lines up with the sunlight, which returns intensely and blinds Cherubi, rendering it vulnerable to the attack. Staravia follows up with Quick Attack and Aerial Ace to knock out Cherubi.
Gardenia calls Cherubi back, praising Ash's tactics before sending out her Turtwig. Ash notices Staravia's slight anger at losing to Turtwig before, wanting redemption. Staravia uses Wing Attack as Turtwig dodges quickly. Ash orders multiple Wing Attacks as Turtwig dodges them all. The tactic grows old and irritates Gardenia, but she realizes too late that Turtwig fell into a trap, backpedaling until it got wedged into a tree. Staravia hits the immobilized Pokémon with Aerial Ace, sending it flying back but not knocking it out. Staravia quickly follows with Wing Attack, but Turtwig's Leech Seed connects and saps Staravia's energy, exposing him to Turtwig's Tackle and knocking him out. Ash recalls Staravia, praising the Pokémon as he brings his Turtwig back out for a rematch.
Ash's Turtwig uses Tackle, but Gardenia's Turtwig dodges and fires Leaf Storm. Ash's climbs into a tree, dodges and starts circling Gardenia's. Ash's tries to attack from behind with Bite, but Gardenia's fires Leech Seed to drain Ash's Turtwig of energy, much like before. Turtwig struggles to rise as Ash quickly orders Synthesis. Gardenia's Turtwig fires Leaf Storm, but Ash's Turtwig quickly dodges and leaps into the sunlight, fully healing. Ash's fires Razor Leaf and hits Gardenia's. Both Turtwig rush each other with Tackle, both hitting and both Pokémon withstanding the attack. Both are exhausted and Ash's almost falters, but Gardenia's Turtwig crumples first. Gardenia praises Ash's bond with his Pokémon as she prepares her last. Still, Brock notices that Leech Seed may be a long-term problem.
Meanwhile, Team Rocket continues digging while the miner stands back. Eventually, they unearth a Red Sphere. The discovery gives Team Rocket renewed digging as they dig out many Spheres, the miner scooping them up. After digging the miner gives Team Rocket lunch. While they eat, the miner slips out with the Spheres. Team Rocket finishes and notices that he has the treasure, but they don't care, wanting to eat more.
Gardenia summons Roserade as her final. Turtwig uses Tackle, but Roserade suavely uses Grass Knot to trip Turtwig before using Weather Ball, turned to a Fire-type move with the sunlight, to torch Turtwig and knock it out. Ash pulls out Aipom as his finale, the Pokémon making a showy entrance as if she was in a Pokémon Contest. Aipom uses Double Team and charges, but Grass Knot eliminates all the duplicates. However, they allow Aipom to jump over the knot and hit with Focus Punch. Roserade fires Magical Leaf, but Aipom easily dodges through the trees. Roserade grabs Aipom with vines from its bouquets and throws her down before using Flash to blind the Pokémon. Aipom uses Focus Punch, but being blind, she simply thrashes about while Roserade steps aside, hitting with Magical Leaf. Aipom gets back up, still blind and thrashing about. Ash tells Aipom to calm down and use her ears instead. Roserade uses another fiery Weather Ball, but Aipom's hearing allows her to use Focus Punch to deflect the attack, and Roserade ends up being blasted by its own Weather Ball. Roserade uses Magical Leaf, but Aipom regains her sight and uses Swift to block the attack before creating a Swift ring around Roserade. Aipom uses Focus Punch to catalyze the attack to converge, hammering Roserade relentlessly as a Contest combination. Aipom quickly follows up with Focus Punch, and Roserade is heaved into a tree, breaking it in the process, before slamming into a wall and fainting, giving Ash the win. Ash hugs Aipom at triumphing on the opponent's home field. At sunset, Gardenia gives Ash the Forest Badge. Ash holds the Badge high as he celebrates with his Pokémon.