Gathering The Gang Of Four! (Japanese: 最初のポケモン！最後の戦い！！ First Pokémon! Final Battle!) is the 44th episode of Pokémon: Battle Frontier.
Ash trades in some of his old Pokémon and brings Bulbasaur, Charizard and Squirtle back. They head up into the mountains for a little training and reminiscing of the past. After stopping yet another Pikachu stealing attempt from Team Rocket, Ash runs into Brandon who is impressed by the four Pokémon. Brandon declares a four-on-four battle this time, so he can see the true strength of the four. Ash agrees, and the next day, the battle begins. Brandon chooses Dusclops and Ash chooses Charizard. Will he finally be able to win?
The heroes wait for something. Oak comes and gives Ash a Poké Ball from Tracey himself. Ash sends his old buddy, Bulbasaur. Pikachu dances with it for a happy reunion then suddenly everyone spots Officer Jenny (with Brock being charmed). She has also Ash's Squirtle, with its sunglasses on. Ash thanks Jenny, as this is least how she can re-pay after the Squirtle Squad saved lives. Ash anticipates one last Pokémon, and from the sky it emerges - Charizard. Ash greets it and Charizard does the same, though he torches Ash and his Pokémon.
May sees Ash's Squirtle and sends her own. Ash's Squirtle uses Water Gun, levitating May's, and May's Squirtle does the same. Brock gives Ash his bag - Ash decided to go to the mountains, to renew his experience when he became a Pokémon trainer. Max reminds Ash Brandon told that the battle is putting the mind of a trainer and Pokémon to challenge, so Ash will go there to learn that lesson, as well as to find his own battle style. Joy gives Ash cookies and now he is ready to go. Ash, Pikachu, Charizard, Squirtle and Bulbasaur wander and spot a field. Charizard throws some logs and Bulbasaur uses Razor Leaf to cut them. The Pokémon catch the pieces of logs and put them together. Squirtle uses Rapid Spin to wave the leaves, while Bulbasaur use Vine Whip and Pikachu with Quick Attack to gather the leaves and put them in the area inside the logs.
Charizard goes on the handmade bed and the leaves go out. Squirtle is annoyed and uses Water Gun, soaking Charizard. Charizard stands up and is attacked by Bulbasaur's Vine Whip. However, Charizard evades and the vine hits Pikachu instead. Pikachu uses Iron Tail, hitting Charizard. Ash goes to stop it, but is hit by Charizard's Flamethrower. Pikachu does the same with Thunderbolt, though it hits everyone. Later, everyone calms down and go to gather food. Ash sees some trees with berries and orders Bulbasaur to use Vine Whip, but Charizard uses Steel Wing to cut the berries from the trees. Squirtle uses Water Gun to push the berries, while Pikachu uses Quick Attack and Bulbasaur with Vine Whip to gather the berries. Later, Ash places some logs and Charizard uses Flamethrower, but it burns all the wood. Ash places more logs, so Charizard blows a tiny spark, allowing the wood to burn.
The Pokémon and Ash are at the campfire. Ash remembers well how he became a trainer and remembers how he got Pikachu, being stubborn to get into the Poké Ball. He turns on Bulbasaur and tells it was protecting the Pokémon and now acts as an ambassador at Oak's lab. Ash knows that Charizard evolved from Charmander then into Charmeleon and got him out of many tough fights victorious. Ash tells Squirtle it was a troublemaker, but now it acts as a firefighter. Ash knows a lot happened since those days. Next days, everyone is practicing and having fun. Team Rocket sees them and Meowth remembers those days. Jessie proposes to catch them all, but with everyone so powerful, James proposes to get Pikachu only. Ash sees a passing wagon of food, with the salesmen being Team Rocket in disguise and goes to them. Jessie tells the battery for making noodles is empty, so they take Pikachu to re-charge it, only to make Ash chase them for betrayal. Team Rocket takes their disguises off and goes inside a metal balloon.
Ash, Bulbasaur and Squirtle go on Charizard, who takes them off. Bulbasaur uses Razor Leaf, but is deflected because of the metal. Charizard uses Flamethrower, making a hot spot and Squirtle uses Water Gun, but nothing happens. So, Ash decides to take turns - Charizard uses Flamethrower and Squirtle with Water Gun, changing turns. The metal begins to crack, and with Bulbasaur's Razor Leaf, Team Rocket falls down, though Ash managed to get Pikachu back. Pikachu uses Thunderbolt, Squirtle with Water Gun, Bulbasaur with Razor Leaf and Charizard with Flamethrower, hitting Team Rocket and blasting them off.
Suddenly, Charizard spots something. It is Pyramid King Brandon, who returned from his expedition. Brandon is impressed by the combination Ash's Pokémon used. Ash tells they are his first Pokémon he got since he became a trainer. Brandon got his Pokémon he was looking for and came to accept Ash's challenge. Brandon proposes this time a 4-on-4 battle, wanting to taste the battle experience of all four Pokémon Ash currently has - Ash accepts the challenge. Next day, Ash and Brandon came back to the Pokémon Center. Scott tells Ash he will be a candidate for becoming a Frontier Brain if he defeats Brandon. Every trainer that has the seven symbols enters the Hall of Fame and can qualify for becoming a Frontier Brain. Ash tells Scott must be a fan of the Battle Frontier and everyone is shocked to hear that Scott is the owner of the Battle Frontier. May and Max are excited to hear that Ash will have his own facility, but he reminds them he has yet to defeat Brandon.
Inside the Battle Pyramid, the roof opens. For his first Pokémon, Brandon sends Dusclops and Ash sends Charizard. Charizard begins with Flamethrower and Dusclops counters with Will-O-Wisp. Charizard uses Steel Wing, but is canceled by Shadow Punch. Charizard retaliates with DragonBreath, hitting Dusclops. Dusclops uses Mean Look, forcing Charizard to battle it. Charizard uses Steel Wing, hitting Dusclops, and with Dusclops so close, it uses Confuse Ray. Because of this, Charizard became confused and Ash cannot call it back due to Mean Look. Dusclops uses Shadow Punch, hurting Charizard. Dusclops uses Will-O-Wisp, hitting Charizard. Ash tells Charizard they have been together for too long and Charizard got rid of confusion and immediately uses DragonBreath to attack. Dusclops retaliates with Will-O-Wisp. Both Pokémon are tired, so Charizard uses Steel Wing, hitting Dusclops and uses Seismic Toss. However, the move is a Fighting-type, so Dusclops disappears. Charizard is defeated by Dusclops' Shadow Punch.
- There was no Trivia Quiz for this episode.
- The ballad version of Battle Frontier is used as background music during the flashback scene.
- Music from Lucario and the Mystery of Mew and an instrumental version of Advance Adventure from Jirachi: Wish Maker are used as background music.
- This is Emily Williams's first time playing Officer Jenny.
- Team Rocket mentions "noodles, hot and fresh off the noodle tree". This may be a reference to the infamous April Fools report on spaghetti trees broadcast on Panorama in 1957.
- Beginning with this episode onwards Michele Knotz provides the voice of Ash's Bulbasaur.
- Ash referred to Pikachu, Squirtle, Charizard, and Bulbasaur as his first Pokémon, when in reality, he caught Butterfree and Pidgeot, who have not been in his possession since Bye Bye Butterfree and Pallet Party Panic, respectively before the latter three.
- When Charizard got back his eyes were a light green then before he used Flamethrower his eyes were blue.
- Charizard got hit by Dusclops' Will-O-Wisp despite the attack has no effect on Fire-types.
- When Ash had a flashback for Charizard he was shown battling Articuno in his Original series clothing instead of Advance Generation series clothing.
- In the English dub, Ash refers to "a lot's happened over the years", despite the fact that he did not age at all, still being ten years old after all the seasons.
Team Rocket refers to waiting for "nine seasons" in the English dub.