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Bakugan: Mechtanium Surge (Japanese version: Bakugan Battle Brawlers: Mechtanium Surge (爆丸バトルブローラーズ： メクタニウムサージ, Bakugan Batoru Burōrāzu: Mekutaniumu Sāji?)) is the fourth and final season of the anime series Bakugan Battle Brawlers, following after Bakugan: Gundalian Invaders. It contains a total of 46 episodes across two arcs; the first arc debuted on February 13, 2011 in Canada and March 5, 2011 in the United States. The second arc debuted September 10, 2011 and contains 20 episodes.
Although a Japanese dub was recorded, Mechtanium Surge never aired in Japan and Korea, and Gundalian Invaders was instead followed by BakuTech! Bakugan in Japan. It wasn't until September 7, 2018 that the Japanese dub was made available via the Chinese streaming site Bilibili.
- Bakugan Interspace gets messy when Dan learns his battling directly threatens Earth. Drago's exposure to Code Eve has infused him with incredible power, causing him to unwittingly release Mechtogan Zenthon, a new mysterious entity that wreaks havoc whenever Drago battles! While Dan attempts to regain control over Drago’s new powers, an insidious enemy builds an army of "Chaos Bakugan" engineered for total world domination! Will Dan be able to get a hold of Drago's power before its to late?
- Bakugan City is off to a peaceful start now that humans have communed with the Bakugan from New Vestroia. This comes to an abrupt end, however, when four Mechtogan who have broken free from their Bakugan start terrorizing the world. Not only that, but some creep called Wiseman has appeared with ancient Bakugan called the Nonets. It's now up to the Battle Brawlers to stop Wiseman, the Nonets, and the Mechtogan's greatest weapon: Mechtavius Destroyer!
- Dan Kuso
- Bakugan: Titanium Dragonoid → Fusion Dragonoid
- Temporary Bakugan: Reptak
- BakuMutant: Mercury Dragonoid / and /
- Baku Sky Raider Combination: Aeroblitz /
- BakuNano: Sonicanon
- Mobile Assault: Zoompha and Rapilator
- Battle Suits: Doomtronic and Defendtrix
- Mechtogan: Zenthon
- Mechtogan Titan: Zenthon Titan
- Mechtogan Destroyer: Dragonoid Destroyer
- Marucho Marukura
- Shun Kazami
- Bakugan: Taylean (Arc 1), Jaakor /Skytruss /Orbeum (Arc 2)
- BakuMutant: Mutant Taylean /
- Baku Sky Raider Combination: Magmafury /
- BakuNano: Hammermor
- Mobile Assault: Zoompha
- Battle Suits: Blasterate and Fortatron
- Mechtogan: Silent Strike (Arc 1) and Thorak (Arc 2)
- Mechtogan Combination: Duomechtra /
- Mechtogan Titan: Faser Titan
- Paige : A Gundalian brawler sent to work with the Battle Brawlers in Arc 1.
- Rafe : A Neathian brawler sent to work with the Battle Brawlers in Arc 1.
- Spectra Phantom : A champion brawler of the Vestals who once wielded the Pyrus attribute, he has become a Darkus brawler on his quest to gain power. Make no mistake though; he is still firmly on the side of good. He comes to the aid of the Battle Brawlers in Arc 1.
- Gunz Lazar : A new brawler who works with the Battle Brawlers in Arc 2.
- Mira Fermin : A Vestal scientist who was once the leader of the Bakugan Battle Brawlers Resistance. She brawls only once in Arc 2 and after that she lends Roxtor to Marucho.
- Bakugan: Roxtor
- Runo Misaki : One of the original Battle Brawlers, Runo makes a temporary brawling return in Arc 2.
- Temporary Bakugan: Aerogan
The main antagonists of Arc 1.
- Mag Mel (Deceased)
- Anubias (Deceased)
- Sellon (Deceased)
- Chaos Bakugan
The main antagonists of Arc 2.
- Wiseman (Deceased)
- First Set of Bakugan: Betadron & Kodokor & Mutabrid & Spatterix (Deceased)
- Second Set of Bakugan: Stronk & Tremblar & Worton & Balista (Deceased)
- BakuFusion Combination: Scorptak / & Volkaos /
- Baku Sky Raider Combination: Gliderak
- First Battle Suit: Combustoid /
- Second Battle Suit: Fortatron /
- Third Battle Suit: Clawbruk /
- Tri-Twisters //
- Bash Brothers /
- Captain Elright
- Ren Krawler : A former Darkus brawler for the Battle Brawlers, he is now the Commander of the Gundalian Army. His Guardian Bakugan is Linehalt .
- Gus Grav : Spectra's right-hand man and a former Subterra brawler for the Vexos. His Guardian Bakugan is Rex Vulcan .
Team Anubias: Brawlers led by Anubias; notably, all of them use Ziperator as their chosen Bakugan.
Team Sellon: An all-girl brawling team led by Sellon.
- Genesis Dragonoid
- Angelo/Diablo Preyas / & /
- Minx Elfin
- Storm Skyress
- Master Ingram
- Blade Tigrerra
- Hammer Gorem
- Alpha Hydranoid
- Fury (Deceased)
- Mechtogan Titan
- Baku Sky Raiders
- Bakugan Battle Suit
- Main article: List of Bakugan: Mechtanium Surge Episodes
- This is the only Bakugan season:
- To feature brawlers and Bakugan hailing from every planet introduced in previous seasons: Earth, New Vestroia, Vestal, Neathia, and Gundalia.
- Without a team of six antagonists brawlers of each Bakugan Attribute (Team Anubias and Team Sellon members are just antihero roles to the protagonist, therefore only their leaders, Anubias and Sellon, respectively are the antagonists along with Mag Mel in Arc 1, while Wiseman is the only antagonist brawler in Arc 2).
- Bakugan with different attributes from previous variations.
- In Arc 2, the main Battle Brawlers used two attributes (Dan: Pyrus and Haos, Shun: Ventus and Darkus, Marucho: Aquos and Subterra).
- In Arc 1, the Battle Brawlers' main female member (Paige) did not have a crush on Dan.
- No gender changes occur on Bakugan debuted during this season, as well as no new Female Bakugan (applies both to Japanese and English dubs).
- Like in the previous season, only Drago and the main antagonist (Razenoid) evolved.
- The season's working title, according to some early material and animation sheets, was Survival Force (サバイバルフォース). Some time later, it was changed to Mechtanium Surge, presumably a portmanteau of "mecha" and "titanium."