The story begins with a young boy named Dan who has never lost a Bakugan match. While in a match against a bully Dan sees a vision of two Bakugan brawling. Is there more to the game than what the players think?

A mysterious Bakugan player named Masquerade, who is ranked at #1 on the list of Bakugan players, is stealing Bakugan from players worldwide. Dan makes an open challenge to Masquerade, and loses two of his Bakugan to this mysterious player, thanks to a Doom Card, which makes a Bakugan disappear forever. Dan is lucky enough to not lose Drago, but might if he loses to Masquerade again

Masquerade teams up with a player with Rikimaru, by giving him a very special Bakugan. When Rikimaru and Dan battle, Drago ends up using a dangerous move to save himself and win the battle. Dan gets angry, and throws Drago into a river, cursing the day they met

Dan has a hard time adjusting to life without Drago. He ends up causing a schoolmate named Ryo to drop his computer and runs away, hurting Ryo's feelings. Masquerade takes advantage of Ryo's hurt feelings, and Ryo beats Dan in a battle

Dan and Runo meet for the first time, outside of the Bakugan website, and realize that they live in the same town. Dan drops his BakuPod, and Runo picks it up, noticing that Dan has battled Masquerade. She goes in his place, but ends up battling a boy named Tatsuya

While at an amusement park, Dan and Runo are invited onstage to assist a magician act by two brothers. Dan picks a card, and realizes it's a Doom Card. The brothers are working for Masquerade, and Dan and Runo get tricked into a battle

Marucho reveals that he secretly moved to Dan's neighborhood, and throws an elaborate welcome party. Masquerade makes a business offer with the famous pop band duo, Jenny and Jewels. The duo crash the welcome party, and challenge the Battle Brawlers

Dan and Marucho fight against the pop star duo, Jenny & Jewels. After a narrow victory, Drago tells the Brawlers about how the Bakugan came to Earth, and how a human entered the Bakugan world of Vestroia

Masquerade manipulates two boys, Kosuke and Takashi, into using his Doom Cards against the Bakugan Battle Brawlers. He promises that he'll reunite their friend Ai with her brother if they help him. Wanting to help their friend, they take the bait and soon run into Runo and Marucho, who are at the airport to pick up their website friend, Alice

Julie and her childhood friend, Billy, go one-on-one in a Bakugan battle. Although Julie's defeated by Billy, she's impressed with his skills and his Bakugan, "Cycloid." They make a great team, and Julie wishes she could befriend a talking Bakugan

Marucho and Runo realize that the combined powers of the Bakugan Brawlers are not enough to defeat Masquerade. Without Dan's knowledge, they visit Shun to try and get him to join. Shun's grandfather tries to get them to leave, but Shun makes a deal

Alice realizes that she may have a connection with the mysterious Hal-G, but doesn't have the courage to tell the other Brawlers. Meanwhile, Dan recalls the last battle he had with Shun. Shun's mother gives Shun a Bakugan, "Skyress", to watch over him

Masquerade has been destroying the Bakugans of kids all over the world, and the Brawlers have to put a stop to it. Reluctantly, Dan accompanies Runo and Marucho to Shun's house to recruit him one more, but find out he's joining Masquerade! Dan accepts the challenge of battle, and with Drago, fights against Shun and Masquerade

Lured by an invitation to celebrate their world class rankings, five of the top ten Bakugan players gather at a mysterious mansion. There they meet Masquerade & the evil Bakugan "Naga". They're put under a spell to take Dan & the other Battle Brawlers out of the picture

The Brawlers finally meet Julie up close and personal, but the mood goes from happy to sad when they see what's happening in Vestroia. Julie and Shun fight with Julie's friend Billy, the 9th ranked Bakugan player, and her neighbor Komba, the 5th ranked Bakugan player, knowing they were tricked by Masquerade to take out Dan and the rest of the Brawlers

Julie is still upset about Billy's betrayal, but tries to put it behind her so she can support the other brawlers. Meanwhile, Shun tells them about a valley similar to Bakugan Valley. Everyone heads there but on the way it is revealed that Shun lied about it being similar, and it was all a ploy to try and see why Masquerade always knows where they are all the time

The Brawlers are having trouble finding the Infinity Core. When they learn that their location might be being broadcasted, they shut off their signal

When Marucho loses his Bakugan to Klaus, he and Runo give chase, and wind up in Masquerade's castle!

After a quarrel between the Brawlers, they all go separate ways. Julie decides to pursue her friend Billy and try to save him from Masquerade's evil ways

When Shun leaves the group, Alice chases after him. Meanwhile Dan goes to take on Masquerade alone

Klaus, Chan-Lee, and Julio return to finish off the Brawlers. Dan, Runo, and Marucho take them on, but what will happen when Klaus uses Marucho's stolen Bakugan?

The Brawlers have been pushed back, but will the return of Preyas and the evolution of Drago be enough to bring them to victory?

Learning that Webmaster Joe is at the hospital, Dan and the other head there. However, while heading for Joe's room, Drago gets lost

Alice helps a little boy defeat his biggest rival

Tensions form between the group of Brawlers when it is believed that one of them is a double agent

The Brawlers head to face Masquerade in one final battle

The Battle Brawlers learn through Webmaster Joe (who was on a trip with his mother) that Masqerade has defeated the World's Top Bakugan players, so they try to come up with a strategy to beat him. The strategy seems to backfire when Masquerade visits Dan's house and gets him to accept a battle. Now the evolved Drago and the evolved Hydranoid will go head-to-head with the loser getting a one-way trip to the Doom Dimension, which is later revealed to be full of Bakugan turned into stone

The Brawlers mourn over the loss of Dan and Drago. Meanwhile, Shun gets a challenge from Masquerade and decides to join Dan in the Doom Dimension. When Skyress learns of this plan, she tries to gather the other Bakugan and try to save Vestroia without putting their human partners in risk

In the Doom Dimension, the Legendary Ancient Warriors of Vestroia prepare to test the powers of the Brawlers, seeing if they are worthy enough to save Vestroia. The Brawlers are separated and Julie is left with Gorem to face the Subterra Warrior, Clayf, and a shadow of her perfect sister, Daisy. With help from Gorem, Julie learns that she isn't her sister and she can only do the best she can do

Marucho must battle the Aquos Elemental Warrior, Frosch, and he is forced to send in Preyus early when he learns he is battling a shadow of himself. Preyus isn't feeling well throughout the battle, but he is able to give Marucho guidance to accepting his past. Marucho knew that he only did what his parents told him to make them happy, but he didn't like to always be so obidient

Shun is stuck with the female Ventus Lord, Oberus, who has summoned a child that looks like Shun's mom to battle. The child convinces Shun to play with her while the sun is still setting, which it never does. Shun must battle himself as well when he is forced to choose between going back or staying in this world with his mother

Runo and Tigrerra must battle a young boy from Runo's past (a smaller version of Dan) summoned by The Haos lord, Lars Lion. The test is for Runo to realize how much she truly treasures her and Dan's friendship/love. When Tigrerra is getting hit by Lars Lion's piercing arrows of light, Runo realises the friendship/love that she treasures and says "We are Friends Forever Dan!" in the English dub, while she says "I love you Dan!" in the Japanese Version

Dan must battle the Pyrus Lord, Apollonier, in order for him and his friends to return to their world. He and Drago soon find out that they're battling a clown. Dan manages to win the battle, but Drago doesn't evolve

Joe is determined to find out where his friends have gone, so he challenges Masquerade to a battle. At first Joe appears to be outmatched, but Wyvern returns to give Joe assistance. The Brawlers also return, and Masquerade realizes his battle is only beginning

Dan tells Shun, Julie, and Marucho that he has yet to pass the test in the Doom Dimension and the only way to have Drago evolve he has to defeat his friends one by one. Julie first battles Dan and Dan wins. Then, he battles Marucho and wins again

Dan's final test is to beat his friends so his Dragonoid can evolve to the next level and become the Ultimate Bakugan. Dan battles Runo and Shun while Masquerade goes to see the Darkus Lord, Exeedra, and he ends up fighting Alice as a mirage

Joe shows up after Dan defeats Julie, Marucho, and Runo for Wyvern to check out Drago's battling skills when Dan and Shun have their battle to finish Dan's test. Meanwhile, the Darkus Lord and Masquerade finish their battle. In the end Drago beats Skyress and becomes the Pyrus Ultimate Dragonoid, and Duel Hydranoid beats the Darkus Lord and evolves into the Darkus Alpha Hydranoid

Alice appears to be disappearing all the time. Dan goes to talk with Marucho, Runo, Shun, and Julie and ends up finding Alice! Alice won't explain anything and leaves. Later, Joe receives a message from Masquerade, and Dan decides he'll take over to fight Masquerade with Drago to end it once and for all with Masquerade

Hal-G appears to explain the origin of Alice and Masquerade. Because she is unable to forgive herself, Alice then disappears. Meanwhile a huge hole opens up in the ocean and weird weather has been happening all throughout the earth

Alice tells Klaus about what she did as Masquerade, and gets pulled into a battle to punish her for sending his Bakugan to the Doom Dimension while she had been Masquerade. However, Klaus was just trying to teach her a lesson, that everyone, and everything must work together in order to create harmony

The Bakugan Battle Brawlers enter Vestroia and realize Vestroia has become a hybrid world where two elements are mixed together to make one element together. They enter the Ventus and Aquos world where they meet Tayghen and Hairadee: two Bakugan of both Ventus and Aquos elements. As they fight, they suddenly see the portal to the next hybrid world of Vestroia is closing and so they agree that Shun and Marucho are to stay in the Ventus and Aquos world to defeat the two Bakugan

As the remaining Brawlers enter the hybrid world of Subterra and Haos, a pair of Subterra/Haos Bakugan sisters named Rabeeder and Tricloid fall in love with Dan. The sisters say the only way out is if they beat them in a race. Dan and Drago win and leave to the next world

Dan and Drago enter the hybrid world of Pyrus and Darkus where the dark army is running rampant. Dan and Drago are saved from Pyrus/Darkus hybrid Bakugans Centorrior and Druman by Nobilion: a Pyrus Tigrerra who is the oldest and wisest of all Bakugan. Nobilion explains how the negative energy has been influencing all of Vestroia, except those who can hide

Alice arrives in Vestroia as Masquerade in order to help her friends. Masquerade finds Dan and he begins to help the weakened Dan and Drago. Centorrior and Druman though are able to counter sound judgment and all the power-ups that their Bakugan are given

The Battle Brawlers have managed to unite each element together, and they are given the blessing as the six new warriors. Hal-G and Naga are still causing chaos over Vestroia though, and now they are attacking Earth with the help of the hybrid Bakugan (Taygen, Hairadee, Rabeeder, Tricloid, Centorrior, and Druman) leading their Bakugan armies. The Brawlers must figure out how to save both worlds

Wayvern puts up an energy shield around Wardington powered by the Infinity Core to hold off Naga and his troops. Meanwhile the Brawlers return and join in the battle to protect all of Earth and defeat Naga before he can join the two cores together. Failure means that both worlds will be destroyed

The battle against Naga's troops continues as Julie and Billy team-up to take on the Subterra/Haos hybrid Bakugan called Tricloid, who has been powered up by Naga negative energy. At first the two seem to be overpowered, but the adaption of each other's battle styles may be what's needed to help them realize how to work as a team again, especially when Naga decides to crash the party. Shuji and Akira also appear trying to get strategies from their sister Nene

Naga's troops have finally infiltrated Wardington after two defeats. Alice discovers that Tricloid's sister Rabeeder is invading the town. Little does she know the one she trained, Christopher, will also get involved in the battle

The return of Naga's Ventus/Aquos servant hybrid Hairadee has brought new troubles for Komba and Shun. While Skyress is trapped in a barrier of ice, Shun reveals his ninja skills to free Skyress and defeat the hybrid. Julio crashes the party and helps the battle

Dan and Runo stand as the only defenses against Centorrior and Druman. As Dan recalls his past battle with them, he realizes they don't have a chance without help. Julie, Billy, Marucho, Klaus, Julio, and Komba also get involved in the battle due to Hal-G doing a blurred transmission by Hal-G posing as Kato

Wayvern is calling to Drago to tell him that she needs help, the top ranked Brawlers must defeat Centorrior and Druman. Meanwhile Naga's negative energy is proving to be too much for Wayvern and Fortress. With Centorrior defeated, the others deal with Druman as Dan and Drago head over to where Naga

As Hal-G releases 5th Paladins, all seems hopeless until the Brawlers send their Bakugan to aid a wounded Drago. They destroy the 5th Paladins as Naga absorbs the 5th Paladins' energies. With the last of his power, Drago fires a brilliant burst of fire